THE  METABOLISM  OF  THE 
FASTING  STEER 


FRANCIS  G.  BENEDICT 

Director 

Nutrition  Laboratory ,  Carnegie  Institution  of  Washington 

AND 

ERNEST  G.  RITZMAN 
Research  Professor  in  Animal  Nutrition 
Nezv  Hampshire  Agricultural  Experiment  Station 


Published  by  the  Carnegie  Institution  of  -Washington 

1927 


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CARNEGIE  INSTITUTION  OF  WASHINGTON 
Publication  No.  377 


1927 


W.  F.  EOBEKTS  COMPANY 
WASHINGTON,  D.  C. 


THE  METABOLISM  OF  THE  FASTING  STEER 


BY 


FRANCIS  G.  BENEDICT 

Director.  Nutrition  Laboratory,  Carnegie  Institution  of  Washington 

AND 

ERNEST  G.  RITZMAN 

Research  Professor  in  Animal  Nutrition 
New  Hampshire  Agricultural  Experiment  Station 


Published  by  the  Carnegie  Institution  of  Washington 

1927 


T 


i 


CONTENTS 


PAGE 


Introduction . 3 

The  significance  of  the  fasting  metabolism  of  cattle .  4 

Determination  of  the  true  fasting  condition . .  8 

The  practical  value  of  fasting .  9 

Other  investigations  on  the  fasting  of  large  animals .  12 

Magendie,  1852 .  12 

Colin,  1862  and  1888. . 12 

Grouven,  1864 .  15 

Ignatief ,  1883  .  20 

Meissl,  1886,  and  Tangl,  1912 .  20 

Capstick  and  Wood,  1922 .  21 

Deighton,  1923 .  22 

Armsby  and  Braman,  1923-24 .  22 

Changes  in  apparatus  and  technique . 24 

Changes  in  the  laboratory  building .  24 

Provision  for  collection  of  individual  urinations .  25 

Additions  to  respiration  chamber .  26 

Changes  in  the  technique  for  measuring  the  respiratory  exchange .  29 

Soda-lime .  29 

Determination  of  proportion  of  air  escaping  through  openings  in  wind  chest  29 

Selection  of  disk  opening  to  meet  specific  experimental  requirements .  31 

Gas-analysis  apparatus .  31 

Importance  of  gas  analysis .  31 

Description  of  gas-analysis  apparatus .  33 

The  physiological  control  of  gas-analysis  apparatus .  34 

Installation  of  the  gas-analysis  apparatus  at  Durham  and  correction  in 

calculation  of  carbon-dioxide  production  necessitated  by  its  use .  34 

Procedure  for  most  accurate  determination  of  respiratory  quotient .  36 

Principles  underlying  control  tests  of  respiration  chamber  by  admitting 

known  amounts  of  carbon  dioxide .  36 

Animals  used  in  experiments .  38 

General  plan  of  research .  39 

Fasting  on  different  planes  of  nutrition .  39 

Subsidiary  problems .  39 

Chronology  of  the  fasting  research .  41 

Details  of  the  experimental  conditions .  41 

Observations  on  mature  steers  C  and  D .  42 

Details  of  the  14-day  fast  in  April  1922 .  43 

General  observations  during  the  14-day  fast .  46 

Summarized  details  of  other  fasts  of  steers  C  and  D .  48 

Observations  on  immature  steers  E  and  F .  51 

Records  of  last  individual  feed  prior  to  each  fast .  52 

Discussion  of  results .  54 

Body-weight .  54 

Lengths  of  fasts  and  nature  of  feed-levels  preceding  them .  55 

Daily  variations  in  body-weight  during  fasting .  56 

Influence  of  long  fasts  at  different  levels  of  nutrition .  56 

Influence  of  short  fasts  at  a  maintenance  level  of  nutrition .  60 

Losses  in  body-weight  during  4-day  fasts  under  similar  conditions .  62 

General  conclusion  with  regard  to  significance  of  changes  in  body-weight. .  63 

Loss  through  the  lungs  and  skin .  63 

Insensible  perspiration  during  food  periods  and  during  24  hours  without 

food .  66 

Insensible  loss  during  3  days  with  food,  followed  by  2  and  3  days  without 

food,  at  a  maintenance  level  of  nutrition .  70 

v 


Vi  METABOLISM  OF  THE  FASTING  STEER 

Discussion  of  results — Continued  page 

Loss  through  the  lungs  and  skin — Continued 

Insensible  loss  during  5  to  14  days  without  food .  71 

Drinking-water .  75 

Feces .  81 

Amount  and  frequency  of  defecations .  82 

Physical  characteristics  of  feces .  89 

Chemical  composition  of  feces .  91 

Dry  matter  in  feces .  91 

Nitrogen  in  feces . 95 

Urine .  97 

Influence  of  fasting  on  amounts  of  urine  excreted .  99 

Amounts  per  24  hours  and  per  hour .  99 

The  frequency  and  amount  of  individual  urinations  during  fasting.  . .  101 

Relation  between  volume  and  dry  matter  of  urine .  103 

Physical  properties  of  the  urine .  103 

Chemistry  of  the  urine .  104 

Urine  analyses  by  other  investigators .  104 

Chemical  methods . .  107 

Statistics  of  results . 107 

Discussion  of  results .  114 

Chlorides  in  urine .  114 

Nitrogen  excreted  in  urine  per  hour .  115 

Partition  of  urinary  nitrogen .  116 

Other  urinary  constituents .  121 

Total  nitrogen  excreted  per  kilogram  of  body-weight  per  24  hours  121 

Creatinine  coefficient .  122 

The  nitrogen  economy  of  steers .  122 

General  conclusions  with  regard  to  the  composition  of  steer’s  urine 

during  fasting .  123 

Nitrogen  loss .  127 

Total  nitrogen  excreted  in  urine  per  day  and  during  the  entire  fast .  127 

Total  nitrogen  loss  during  fasts  of  5  to  14  days .  129 

Body  measurements,  general  body  conditions,  and  physiological  functions .  130 

Body  measurements .  130 

General  body  conditions .  133 

General  behaviour  of  fasting  steers .  133 

General  appearance .  136 

Heart-rate .  137 

Respiration-rate .  141 

Rectal  temperature .  142 

Skin  temperature . . .  143 

Gaseous  metabolism  and  energy  relationships .  144 

Metabolism  measurements  actually  made  or  computed .  144 

Conditions  prerequisite  for  comparable  measurements  of  metabolism .....  150 

The  physiological  comparison  of  animals .  152 

Comparison  on  the  basis  of  live  body-weight .  152 

Comparison  on  the  basis  of  body-surface .  153 

Method  of  estimating  the  surface  area  of  fasting  steers .  153 

Method  of  presenting  the  gaseous  metabolism  data .  156 

Metabolism  during  fasting .  158 

Respiratory  quotient .  158 

Carbon-dioxide  production .  161 

Tabular  presentation  of  data  for  long  and  short  fasts .  165 

Course  of  the  heat-production  during  fasts  of  5  to  14  days,  at  different 

levels  of  nutrition .  171 

Total  heat-production  per  24  hours .  171 

Heat-production  per  500  kg.  of  body-weight  per  24  hours .  174 

Heat-production  per  square  meter  of  body-surface  per  24  hours .  .  .  179 


CONTENTS 


Vll 

Discussion  of  results — Continued  page 

Gaseous  metabolism  and  energy  relationships — Continued 
Metabolism  during  fasting — Continued 

Heat-production  in  2-day  fasts  at  a  maintenance  level  of  nutrition .  180 

Measurement  of  fasting  metabolism  in  3  consecutive  24-hour  periods . . .  185 

Comparison,  of  the  metabolism  during  2  days  on  food,  followed  by  2  days 
without  food,  at  maintenance  and  submaintenance  levels  and  at  high 

and  low  environmental  temperatures .  192 

Influence  of  quantity  and  character  of  ration  upon  metabolism  during 

feeding .  196 

Influence  of  quantity  and  character  of  ration  upon  metabolism  during 

fasting .  198 

Influence  of  environmental  temperature .  200 

Influence  of  lying  and  standing .  202 

The  basal  metabolism  of  steers .  203 

Incidence  of  plateau  in  metabolism  of  steers  after  cessation  of  active 

digestion .  204 

The  metabolic  plateau  of  the  same  animal,  when  fasting  under  different 

conditions .  206 

Conclusions  regarding  the  incidence  and  the  level  of  the  plateau  in 

metabolism  of  steers .  208 

Computation  of  the  fasting  katabolism  of  steers  from  experiments  on 

two  different  feed-levels .  209 

Correction  of  basal  katabolism  to  a  standard  day  as  to  standing 

and  lying .  211 

Inherent  error  in  method  of  computing  the  fasting  katabolism  from 

experiments  on  two  different  feed- levels .  213 

The  minimum  heat-production  of  steers  per  square  meter  of  body- 

surface  per  24  hours .  218 

The  physiological  significance  of  surface  area  and  its  relationship 

to  heat-production .  221 

Influence  of  the  ingestion  of  food .  222 

The  immediate  reaction  to  the  ingestion  of  food  after  a  prolonged  fast  222 

The  metabolic  stimulus  of  feeding-stuffs .  223 

The  standard  metabolism  of  steers  under  different  conditions .  228 

Factors  other  than  the  nutritive  level  which  affect  the  standard 

metabolism . 228 

Level  of  the  standard  metabolism  at  the  beginning  of  the  different 

fasts .  230 

Influence  of  environmental  temperature  upon  standard  metabolism ....  230 

Influence  of  level  of  nutrition  upon  the  standard  metabolism .  231 

Summary .  235 

Subject  index .  241 

Author  index .  246 


, 


ILLUSTRATIONS 


Fig.  page 

1.  Arrangement  of  laboratory  rooms .  24 

2.  Diagram  of  feed-chute,  feed-box,  feces-chute,  and  provision  for  collection  of  urine 

in  respiration  chamber .  26 

3.  Diagram  of  the  Carpenter  apparatus  for  the  exact  analysis  of  atmospheric  and 

chamber  air .  33 

4.  Individual  defecations  of  steers  C  and  D  during  fasts  in  April  and  November 

1922  and  March  1924 .  87 

5.  Feces  voided  by  steer  C  on  the  sixth  day  of  fasting,  November  10,  1923 .  88 

6.  Feces  voided  by  steer  D  on  the  fifth  day  of  fasting,  March  8,  1924 .  88 

7.  Individual  urinations  of  steers  C  and  D  during  fasts  in  April  and  November,  1922, 

and  March  1924 .  102 

8.  Body-surface  in  square  meters  referred  to  live  weight  in  kilograms .  155 


vm 


THE  METABOLISM  OF  THE  FASTING  STEER 


By  F.  G.  Benedict  and  E.  G.  Ritzman 


From  the  Nutrition  Laboratory  of  the  Carnegie  Institution  of  Washington, 
at  Boston,  Massachusetts,  and  the  New  Hampshire  Agricultural 
Experiment  Station,  Durham,  New  Hampshire 

With  eight  text  figures 


1 


INTRODUCTION 

Much  of  the  research  in  the  field  of  human  nutrition  has  been  based  upon 
experiments  made  during  complete  fasting.  In  this  condition  the  minimum 
metabolism  or  the  degree  to  which  the  body  is  drawn  upon  for  maintenance 
of  the  life  processes  can  be  determined,  and  the  capacity  of  any  food  or 
ration  to  protect  the  body  from  such  drafts  can  then  immediately  be 
referred  to  the  fasting  metabolism.  The  seemingly  inherent  difficulties  in 
subjecting  a  ruminant  with  large  paunch  to  fasting  has  deterred  most 
workers  in  animal  nutrition  from  such  tests,  although  as  early  as  1862 
Hubert  Grouven  made  his  classic  experiments  with  oxen,  one  of  which  fasted 
for  8  days.® 

In  the  management  of  domestic  livestock,  farmers  in  the  United  States 
have  been  educated  to  believe  that  regular  and  liberal  feeding  forms  the 
basis  of  good  economic  practice.  This  belief  has  not  uncommonly  led  to 
the  inference  that  animals  deprived  entirely  of  food,  even  for  a  relatively 
short  time,  would  endure  physical  hardship,  suffering,  and  injury.  The 
error  of  such  a  conclusion  is  best  illustrated  by  a  consideration  of  the  life 
habits  of  wild  animals,  such  as  the  deer,  which  is  also  a  ruminant.  Deer 
pass  through  long  periods  of  deprivation,  when  food  is  scant  or  sometimes 
entirely  lacking,  and  on  the  whole  survive  in  excellent  shape,  with  remark¬ 
able  vigor,  unimpaired  by  such  experiences.  As  pure  a  priori  reasoning,  it 
would  seem  logical  to  assume  that  the  length  of  time  during  which  an  animal 
can  comfortably  go  without  food  would  be,  at  least  in  part,  determined  by 
its  storage  capacity,  for  until  the  food  in  the  digestive  tract  is  used  up, 
complete  fasting  does  not  begin.  The  camel,  due  to  his  capacity  for  storage 
of  water,  has  long  been  used  for  desert  journeys.  In  a  like,  though  limited, 
manner  the  ox  has  a  storage  capacity  for  forage  and  can  exist  without 
having  his  food  replenished  for  several  days  before  this  storage  is  entirely 
depleted.  The  ox,  however,  is  seldom  forced  by  man  to  make  use  of  this 
provision  of  nature,  because  it  is  usually  more  profitable  not  to  do  so. 

The  history  of  experimental  fasting  also  shows  that  nature  has  provided 
animal  life  with  a  wide  measure  of  protection  against  the  contingency  of 
food  shortage.  The  almost  incredible  length  of  time  that  the  dog  has  been 
able  to  withstand  fasting,  notably  in  the  experiments  of  Howe  and  Hawk* * 6 
whose  dog  fasted  for  over  100  days,  and  the  long  intervals  known  to  elapse 
between  the  taking  of  food  by  cold-blooded  animals,  such  as  the  large 
python  in  the  New  York  Zoological  Park0  and  the  snake  studied  by  Valen¬ 
ciennes, d  lead  to  the  inference  that  fasting  per  se  is  not  ordinarily  injurious, 
provided  it  is  not  carried  to  too  great  an  extreme.  All  animal  life  does  not, 
of  course,  possess  the  same  degree  of  resistance  to  fasting,  but  it  is  safe  to 
say  that  the  resistance  is  far  greater  than  is  generally  supposed.  In  the  last 

°  Grouven,  Physiologisch-chemische  Fiitterungsversuche.  Zweiter  Bericht  iiber  die  Arbeiten 

der  agrikulturchemischen  Versuchsstation  zu  Salzmiinde,  Berlin,  1864. 

6  Howe  and  Hawk,  Am.  Journ.  Physiol.,  1912,  30,  p.  174;  Howe,  Mattill,  and  Hawk,  Journ. 
Biol.  Chem.,  1912,11,  p.  103. 

e  Unpublished  experiments  of  Mr.  Raymond  L.  Ditmars  at  the  New  York  Zoological  Park. 

d  Valenciennes,  Compt.  rend.,  1841,  13,  p.  126. 

3 


4 


METABOLISM  OF  THE  FASTING  STEER 


three  or  four  decades  much  experience  has  been  secured,  both  in  the  labora 
tory  and  also  (as  an  incidental  result  of  the  recent  World  War)  in  large 
communities,  regarding  the  effect  upon  humans  of  entire  lack  of  food  or  of 
a  greatly  reduced  food  intake.  This  experience  has  indicated  that,  although 
in  many  instances  serious  disturbances  may  arise  from  such  food  shortage, 
unless  the  lack  of  food  occurs  at  a  very  early  stage  of  life,  complete  recupera¬ 
tion  generally  takes  place  fairly  rapidly  when  sufficient  food  is  again 
available.  Indeed,  we  have  seen  that  laboratory  experience  with  animals 
shows  innumerable  instances  of  partial  and  of  complete  fasting  for  several 
months  without  ill  results,  and  numerous  observations  on  humans  show 
that  with  some  individuals  complete  controlled  fasting  may  progress  without 
injurious  results  for  from  one  week  to  one  month.0 

The  Nutrition  Laboratory  has  for  many  years  experimented  with  fasting. 
It  has  studied  men  who  fasted  for  from  8  to  31  days,  geese  which  were 
deprived  of  food  for  30  days,  and  snakes  which  voluntarily  refused  food  for 
a  period  of  months.  The  general  conclusion  drawn  from  these  experiments 
is  that  such  fasting  was  not  accompanied  by  pain,  distress,  or  any  untoward 
after-effects.  This  conclusion  has  been  further  confirmed  by  the  extended 
experience  of  the  Nutrition  Laboratory  in  studying  the  effects  of  under¬ 
nutrition  upon  a  large  group  of  young  men.  These  men  showed  many 
striking,  if  not  profound,  physiological  alterations  due  clearly  to  under- 
nutrition,  without  a  corresponding  change  in  intellectual  and  physical 
powers.6 

Having  thus  demonstrated  the  safety  with  which  fasting  and  under- 
nutrition  may  be  practiced  in  humans,  perhaps  the  most  sensitive  animal, 
the  Nutrition  Laboratory,  in  cooperation  with  the  New  Hampshire  Agri¬ 
cultural  Experiment  Station,  undertook  a  study  of  undemutrition  in  large 
steers,  a  report  of  which  was  recently  issued.0  This  study  likewise  indicated 
clearly  that  undernutrition  causes  no  distress  or  pain  in  cattle.  An  attempt 
to  subject  large  ruminants  to  complete  fasting  seemed,  therefore,  in  no  sense 
open  to  serious  objection. 

THE  SIGNIFICANCE  OF  THE  FASTING  METABOLISM 

OF  CATTLE 

As  the  result  of  feeding  there  occurs  in  the  animal  body  a  series  of  energy 
transformations  which,  from  the  economic  point  of  view,  represent  at  least 
four  distinct  phases  of  vital  activity. 

(1)  The  maintenance  of  life  or  body  equilibrium. 

(2)  Productive  use  above  the  maintenance  requirements,  such  as  that  for 
growth,  milk  production,  and  body  deposits. 

(3)  Muscular  activity,  such  as  the  productive  muscular  work  of  draft 
horses  or  oxen. 

(4)  The  energy  incident  to  the  conversion  of  food  or  digestion. 

The  first  bears  directly  on  the  extent  to  which  food  may  serve  to  protect 
body-tissue  from  being  drawn  upon  to  maintain  life  and  to  replace  body- 
tissue  so  used.  The  second  relates  to  the  extent  to  which  food  may  be 

°  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  203,  1915. 

1  Benedict,  Miles,  Roth,  and  Smith,  Carnegie  Inst.  Wash.  Pub.  No.  280,  1919. 

*  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923. 


I 


INTRODUCTION  5 

converted  into  surplus  body-tissue  or  into  other  usefully  productive  pur¬ 
poses  above  the  needs  of  maintenance.  Muscular  work,  when  external,  is 
a  true  production  which,  may  be  of  value,  as  in  the  draft  animal,  or  may 
be  waste,  as  in  the  restlessness  or  activity  of  the  animal,  even  when  in  the 
stall.  The  internal  muscular  work  of  respiration,  circulation,  and  digestive 
processes  is  an  integral  part  of  the  necessary  life  processes  of  the  animal, 
and  hence  a  factor  of  maintenance.  Productive  muscular  work  must  always 
be  considered  as  a  separate  item,  since  it  is  performed  at  the  expense  of  the 
production  of  body-tissue.  It  is  equally  clear  that  if  the  cost  of  food  con¬ 
version,  that  is,  the  increase  in  heat-production  following  the  ingestion  of 
food,  represents  energy  which  does  not  serve  to  protect  body-tissue  or  to 
form  body-tissue,  it  must  be  regarded  as  an  overhead  cost  physiologically. 

The  significance  of  studying  the  fasting  metabolism  under  comfortable 
stall  conditions,  therefore,  is  that  under  these  conditions  the  third  and  fourth 
uses  of  the  total  energy  production  are  eliminated,  and  it  is  possible  to 
determine  the  capacity  of  the  energy  in  food  to  meet  the  first  two  needs. 

Maintenance  or  fasting  metabolism — The  first  function  of  food  is  to 
maintain  life.  Since  the  food,  as  eaten,  requires  considerable  elaboration, 
cleavage,  and  resynthesis,  an  additional  amount  must  be  allowed  to  meet 
the  energy  expended  in  the  conversion  of  the  food ;  otherwise  the  ration  will 
be  deficient  by  that  amount  and  body-tissue  will  be  drawn  upon  to  make  up 
for  the  deficit.  If  no  food  at  all  is  given,  the  entire  amount  of  energy  neces¬ 
sary  to  maintain  life  will  be  supplied  by  body -tissue.  In  this  case  the  total 
energy  production  represents  solely  that  quota  of  energy  use  which  is  neces¬ 
sary  to  maintain  life,  no  overhead  cost  being  included  because  no  food  is 
present.  This  fasting  katabolism  is  the  basic  constant  which  must  first  be 
determined,  before  the  energy  uses  for  productive  efforts  and  for  overhead 
service  can  be  reckoned  separately.  Furthermore,  it  is  only  on  this  fasting 
basis,  when  the  metabolism  indicates  the  daily  heat  requirements  necessary 
to  maintain  life,  that  a  comparison  between  different  species  or  between 
animals  differing  in  size  or  body-build  is  of  any  significance. 

Productive  use  of  food  is  represented  by  that  measure  of  efficiency  with 
which  the  animal  is  able  to  convert  food,  given  in  excess  of  its  own 
need  for  maintaining  body  equilibrium,  into  some  useful  product  such  as 
growth,  meat,  milk,  wool,  or  work.  It  is  for  this  surplus  production  that 
domestic  animals  are  kept,  and  it  is  on  the  basis  of  this  surplus  production 
that  the  efficiency  of  animals  and  of  feeds  is  economically  of  variable 
significance.  From  a  quantitative  point  of  view  the  value  of  any  given 
ration  is  in  large  part  determined  by  the  proportion  of  potential  energy 
which  it  yields  for  conversion  into  body  structure  or  milk.0  A  sufficient 
amount  of  protein  is  no  less  essential  to  carry  on  these  functions  success¬ 
fully  than  is  a  sufficient  amount  of  energy.  Yet  quantitatively  the  protein 
requirement  never  exceeds  one-fourth  of  the  energy  requirement,  even  for 
growth  or  milk  production,  and  for  fattening  purposes  the  quantitative  rela¬ 
tionship  between  energy  and  protein  may  even  exceed  a  ratio  of  10  to  1. 
The  more  recent  knowledge  regarding  food-accessory  factors  is  increasingly 
challenging  attention  also,  but  as  far  as  now  known  their  quantitative 


•  Armsby,  Journ.  Agric.  Sci.,  1919,  9,  p.  182. 


6 


METABOLISM  OF  THE  FASTING  STEER 


importance  is  too  small  to  be  measurable.  Hence  it  is  not  surprising  that  in 
general  studies  on  nutrition  the  energy  problems  must  continue  to  play  the 
dominant  role.  I 

Muscular  activity  is  a  factor  which  makes  an  exceedingly  marked  demand  I 
on  the  use  of  energy.  So  far  as  tissue  katabolism  is  concerned,  there  are  1 
several  classes  of  muscular  activity.  Thus,  the  muscular  activity  which  is  1 
involved  in  the  mastication  and  general  manipulation  of  food  in  the 
animal  body  is  of  a  more  or  less  involuntary  character,  and  is  to  some 
extent  proportional  to  food  conversion,  in  behalf  of  which  it  is  entirely 
exerted.  It  is  an  overhead  expense,  because  it  uses  body-tissue  which  must 
be  replaced  by  food,  and  as  it  can  not  be  modified  or  controlled  while 
animals  are  being  fed,  the  determination  of  its  quantitative  demands  on 
energy  becomes  complicated.  Other  types  of  muscular  activity  of  a  more  | 
voluntary  nature  are  exhibited  and  measurable  by  the  extent  of  visible  . 
manifestations,  such  as  general  restlessness  and  moving  around.  Such  j 
movements  are  in  no  sense  contributory  to  food  conversion.  This  type  of  y 
muscular  exertion  may  result  in  a  greatly  variable  energy  expenditure  under  | 
ordinary  conditions,  not  only  when  animals  are  grazing  and  thus  obliged  to 
move  about  according  to  the  quality  of  pasturage,  but  also  during  the 
season  of  stall  feeding,  if  they  are  allowed  daily  exercise.  Unless  the  pri¬ 
mary  object  in  feeding  animals  for  a  usefully  productive  purpose  is  to  enable 
them  to  perform  physical  exertion  or  work,  as  in  the  case  of  horses,  mules, 
and  work  oxen,  this  type  of  muscular  activity,  if  permitted,  also  becomes 
an  overhead  charge.  In  the  study  of  nutrition  problems,  where  muscular 
exertion  is  not  the  objective,  this  factor  can  easily  be  controlled  within 
reasonable  limits  by  placing  the  animals  in  stalls,  so  that  voluntary  mus¬ 
cular  exertion  is  represented  only  by  the  tension  due  to  standing  and  the 
effort  of  changing  from  the  lying  to  the  standing  position. 

The  energy  involved  in  food  conversion,  which  is  an  overhead  item, 
includes  the  energy  expended  in  the  actual  physiological  processes  of  masti¬ 
cation,  digestion,  and  manipulation  of  food  in  the  alimentary  tract.  It  also 
includes  a  large  daily  energy  production  which  occurs  immediately  when 
food  is  ingested  or  is  present  in  the  alimentary  tract,  inducing  a  stimulating 
effect  on  the  body  cells.  Since,  in  this  conversion  of  food,  energy  is  con¬ 
sumed  which  would  otherwise  contribute  to  tissue  equilibrium  or  towards 
other  usefully  productive  service,  this  energy  must  be  regarded  as  waste, 
just  as  undigested  feed  residues  or  the  gases  produced  by  fermentation  are 
regarded  as  waste. 

When  food  enters  the  alimentary  tract  there  begins  immediately  a  process 
which  involves  muscular  motion,  and,  as  is  known,  all  muscular  motion  is 
accompanied  by  heat-production.  Even  the  act  of  mastication  results  in  a 
certain  definite  consumption  of  energy.  The  difficulties  of  measuring  this 
latter  exactly  have  led  to  wide  divergence  in  the  conception  of  the  energy 
cost  of  mastication.  With  man  a  distinct  rise  in  metabolism  has  been 
noticed  as  a  result  of  chewing  an  inert,  insoluble  substance  such  as  rubber 
or  gum.®  The  subsequent  processes  of  deglutition,  peristalsis,  expulsion  of 


“Benedict  and  Carpenter,  Carnegie  Inst.  Wash.  Pub.  No.  261,  1918,  p.  139. 


INTRODUCTION 


7 


feces,  and,  in  the  case  of  ruminants,  rumination,  all  involve  muscular  actions 
and,  theoretically  at  least,  heat-production. 

The  earliest  studies  with  ruminants  showed  that  there  were  great  increases 
in  energy  production  following  the  ingestion  of  food,  increases  which  were 
at  first  attributed,  naturally  enough,  to  the  slow  passage  of  food  through 
the  alimentary  tract  and  the  vast  amount  of  material  to  be  worked  over 
by  peristaltic  action.  Indeed,  Zuntz  and  his  school  believed  that  the  increase 
was  due  in  large  part  to  the  muscular  activity  involved  in  the  propulsion 
of  food  from  the  mouth  to  the  anus,  although  they  freely  recognized  that 
there  were  subsidiary  energy  transformations  necessitated  by  glandular  and 
other  processes.  In  the  experiments  with  ruminants,  the  feed  residues  to  be 
moved  through  the  intestinal  tract  were  very  large,  the  indigestible  matter 
amounting  with  rough  fodders  to  50  per  cent  of  the  intake.  On  the  other 
hand,  in  experiments  with  humans  and  dogs,  the  diet  contained  a  relatively 
small  amount  of  indigestible  material,  and  hence  the  increment  due  to  the 
process  of  digestion  could  not  logically  be  attributed  to  the  muscular  activity 
of  moving  a  large  food  ballast.  Furthermore,  a  careful  study  of  the  effect 
of  individual  nutrients,  protein,  fat,  and  carbohydrate,  showed  that  protein 
caused  a  much  greater  rise  in  the  heat-production  of  the  dog  or  of  man 
than  either  carbohydrate  or  fat.  This  difference  was  ascribed  by  Rubner 
to  the  “specific  dynamic  action”  of  the  foodstuffs,  and  the  two  schools  of 
Zuntz  and  Rubner  have  had  long  controversial  discussions  as  to  the  causes 
for  the  increase  in  metabolism  following  the  ingestion  of  food.  It  is  not  at 
all  surprising  that  Zuntz,  with  his  intimate  knowledge  of  the  physiology  of 
the  ruminant,  should  have  attributed  the  large  increase  noted  with  these 
animals  to  muscular  activity  in  connection  with  their  enormous  fecal  masses 
and  ballast.  The  amount  of  protein  involved  in  the  ration  of  many  of  these 
ruminants,  and  particularly  in  some  of  the  special  experiments  of  Zuntz, 
was  so  small  as  almost  to  rule  out  any  material  influence  of  protein  per  se. 
On  the  contrary,  in  Rubner’s  experiments  on  dogs,  which  were  given  large 
masses  of  nearly  pure  protein,  the  large  increases  noted  in  metabolism  could 
not  have  been  caused  by  the  muscular  action  due  to  the  process  of  digestion. 

Since  the  promulgation  of  these  earlier  theories  much  experimental  work 
has  accumulated,  chiefly  with  humans  and  laboratory  animals,  but  at  the 
present  date  information  with  regard  to  large  ruminants  is  still  sadly 
lacking.  It  is  a  fact,  however,  that  the  ingestion  of  food  usually  produces  a 
marked  increase  in  the  heat-production  of  ruminants.  Hence,  in  estimating 
the  energy  value  of  a  given  ration,  one  must  immediately  recognize  that  the 
increase  in  metabolism  incidental  to  the  digestion  of  the  ration  does  not 
contribute  to  the  production  of  either  tissue  or  milk  and  must  logically  be 
charged  as  an  expense  in  the  preparation  of  the  raw  food  material  for 
deposition  of  tissue  or  for  production  of  milk. 

Although  the  processes  of  digestion,  absorption,  and  peristalsis  theo¬ 
retically  call  for  a  consumption  of  energy,  the  demand  for  this  purpose  is 
probably  very  small.  On  the  other  hand,  it  seems  clearly  established  that 
acid  bodies  are  absorbed  from  the  food  which  circulate  in  the  blood  and 
increase  cell  activity  markedly,  so  that  when  food  is  supplied  the  cells  are 
stimulated  to  a  metabolic  level  considerably  above  that  of  the  fasting  animal. 


8 


METABOLISM  OF  THE  FASTING  STEER 


This  increase  in  cell  activity  resulting  from  the  ingestion  of  food  is  likewise  ‘ 
of  no  use  to  the  body  in  preventing  the  oxidation  of  body  material  or  in 
supplying  energy  for  storage.  Hence  the  energy  represented  by  this  increase 
in  cell  activity  must  also  be  deducted  from  the  energy  value  of  the  food 
absorbed.  It  is  not  possible  at  the  present  date  to  explain  clearly  all  the 
processes  of  digestion  and  the  path  taken  by  each  individual  component  of 
the  absorbed  food.  The  investigations  of  Graham  Lusk  at  the  Cornell  Uni¬ 
versity  Medical  School  are  fundamental  in  this  line.  Thus  far,  unfortu¬ 
nately,  they  have  been  confined  chiefly  to  the  processes  of  digestion  in  the 
dog,  with  certain  observations  on  man.  A  full  understanding  of  the  influ¬ 
ence  of  such  products  upon  cell  metabolism  in  ruminants,  however,  can  not 
be  obtained  by  work  upon  carnivorous  animals  alone.  The  study  of  the 
after-effects  of  digestion  in  ruminants  during  the  first  few  days  without 
food,  i.  e.,  the  beginning  stage  of  fasting,  is  therefore  of  great  importance, 
because  it  represents  an  entirely  different  type  of  digestive  process. 

DETERMINATION  OF  THE  TRUE  FASTING  CONDITION 

If  food  is  withheld,  the  processes  of  metabolism  to  be  measured  will 
eventually  become  reduced  to  the  process  of  katabolism.  With  animals 
having  rapid  digestion  and  absorption  from  the  alimentary  tract  this  stage 
is  reached  fairly  soon,  but  with  ruminants  there  may  be  a  period  of  several 
days  when  the  large  ballast  in  the  intestinal  tract  continues  to  add  some¬ 
what  to  the  energy  metabolism.  Ruminants  especially,  therefore,  should 
be  studied,  if  possible,  in  the  fasting  condition  in  order  to  secure  infor¬ 
mation  on  many  problems.  The  determination  of  the  true  fasting  con¬ 
dition,  even  with  humans,  is  difficult.  In  the  last  analysis  such  a  deter¬ 
mination  resolves  itself  into  an  attempt  to  find  out  for  how  many  hours 
after  the  last  meal  the  processes  of  digestion  and  absorption  are  active.  The 
criteria  for  designating  the  exact  time  when  true  fasting  begins  are  by  no 
means  sharply  defined.  In  the  case  of  adult  humans  cessation  of  digestion 
has  commonly  been  considered  to  occur  12  hours  after  eating,  provided  that 
the  last  meal  has  not  contained  too  large  a  proportion  of  protein.  With 
infants,  the  period  when  absorption  and  resynthesis  of  absorbed  material 
stop  and  the  body  begins  to  live  solely  upon  previously  formed  body  mate¬ 
rials  is  determined  only  with  difficulty. 

One  of  the  best  indices  of  the  true  fasting  stage  with  humans  is  the 
appearance  of  certain  metabolic  products,  chiefly  in  the  breath  and  urine, 
in  the  form  of  acid  bodies.  It  is  commonly  believed  that  the  appearance  of 
acid  bodies  implies  that  free  carbohydrate  is  no  longer  available  for  com¬ 
bustion,  although  blood-sugar  is  always  present  in  normal  amounts.  In  all 
probability  the  formation  of  these  acid  bodies  is  dependent  not  only  upon 
the  exhaustion  of  the  supply  of  food  carbohydrate,  but  upon  the  depletion 
or  a  heavy  drain  on  the  ever-existing  store  of  glycogen.  Because  of  this 
intermediary  stage  of  depletion  of 'carbohydrate  storage,  therefore,  even 
these  acid  bodies  are  by  no  means  sharp  indices  of  the  moment  when  fasting 
begins  and  the  metabolism  due  to  food  particles  ceases. 

With  infants,  the  onset  of  the  true  fasting  condition,  when  food  is  not 
given,  is  rapid.  Thus,  after  a  relatively  short  time  of  fasting,  acid  bodies 


INTRODUCTION 


9 


may  appear.  This  fact  has  complicated  greatly  the  determination  of  the 
true  fasting  metabolism  of  infants.  The  difficulty  is  by  no  means  so  great 
in  the  case  of  adult  humans.  A  lengthy  series  of  experiments  has  shown 
that  the  amount  of  glycogen  drawn  upon  during  the  first  day  after  the  com¬ 
plete  withdrawal  of  food  may  be  as  much  as  100  or  200  grams,  and  that 
thereafter  a  continually  decreasing  amount  is  withdrawn  until  about  the 
fifth  day,  when  but  about  20  grams  enter  into  the  metabolism.®  Fasting 
metabolism,  therefore,  may  not  be  described  solely  as  a  protein-fat  katabo- 
lism,  but  more  particularly  as  a  metabolism  in  which  body  material  fur¬ 
nishes  the  sole  supply  of  energy.  This  material  may  or  may  not  be  organ¬ 
ized  body  material,  but  at  least  it  represents  material  which  has  passed  out 
of  the  alimentary  tract  and  has  been  absorbed,  ready  for  further  elaboration 
or  combustion,  as  the  case  may  be. 

Because  of  the  prolonged  digestion  of  large  food  residues  by  ruminants, 
the  attempt  to  establish  a  point  as  sharply  defined  as  that  just  mentioned 
for  humans  has  a  greater  element  of  uncertainty.  The  index  of  the  forma¬ 
tion  of  acid  bodies  may  not  be  used  in  this  case,  for  it  is  commonly  believed 
that  a  large  proportion  of  the  fermentations  taking  place  in  the  alimentary 
tract  of  the  ruminant  are  accompanied  by  the  formation  of  fatty  acids 
which  are  subsequently  absorbed  and  burned.  However,  knowledge  of  the 
influence  upon  metabolism  of  the  absorption  of  fatty  acids,  and  particularly 
knowledge  regarding  the  appearance  of  fatty  acids  in  the  urine,  is  not 
without  value  in  studying  the  metabolism  of  ruminants,  as  is  shown  in  the 
consideration  of  the  chemistry  of  the  urine  of  steers  (see  p.  124). 

Since  a  clear  understanding  of  practically  all  the  physiological  processes 
of  the  animal  organism,  such  as  the  digestion  of  food,  the  maintenance  level 
of  metabolism,  and  the  productive  level  of  metabolism,  can  be  obtained  only 
by  reference  to  some  level  of  metabolism  of  the  animal  which  may  be  con¬ 
sidered  as  reasonably  fixed  and  well  known,  the  determination  of  the  exact 
time  when  the  true  fasting  katabolism  of  large  ruminants  begins  is  therefore 
an  important  physiological  study.  In  an  earlier  report  such  a  reasonably 
fixed  metabolism  was  defined  as  the  “standard  metabolism,”* 6  and  the  begin¬ 
ning  of  the  second  24  hours  after  the  last  meal  was  arbitrarily  selected  as 
the  period  of  time  when  the  greater  part  of  the  disturbing  influence  caused 
by  the  presence  of  food  would  have  disappeared.  With  humans,  12  hours 
is  considered  a  sufficient  lapse  of  time,  but  it  was  obvious  that  with 
ruminants  the  slower  passage  of  food  through  the  intestinal  tract  would 
make  it  inevitably  necessary  to  lengthen  this  time,  although  it  was  fully 
appreciated  that  the  true  fasting  stage  of  metabolism  could  hardly  have 
been  reached  in  24  hours. 

THE  PRACTICAL  VALUE  OF  FASTING 

The  fact  that  a  number  of  divergent  feeding  standards  are  now  in  use  is, 
in  itself,  sufficient  testimony  that  no.  standard  has  as  yet  been  established 
which  will  meet  conditions  differing  essentially  from  those  under  which  it 
was  determined.  No  doubt  the  main  contributing  causes  for  this  failure  to 

°  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  77,  1907,  p.  463. 

6  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  197. 


10 


METABOLISM  OF  THE  FASTING  STEER 


supply  the  producers  of  livestock  with  a  standard  of  values  of  different 
feeds  to  meet  the  varying  requirements  in  livestock  production  are  found 
basically  in  the  fact  that  the  varying  ways  in  which  the  animal  organism 
expends  energy  have  been  either  entirely  ignored  or  have  been  computed  on 
the  basis  of  false  assumptions,  so  that  the  true  net  use  of  food  for  conversionj 
into  body-tissue  was  not  actually  obtained.  In  other  words,  the  physio¬ 
logical  accounting  has  been  faulty  or  incomplete  in  both  cases.  When  the 
total  available  energy  is  accepted  as  the  measure  of  productive  use,  the  error 
lies  in  a  disregard  of  the  fact  that  different  feeds  have  different  conversion 
values.  Thus,  wrong  net  values,  which  alone  are  the  measure  of  the  effect 
of  feed  on  animal  tissue,  were  obtained.  Consequently,  since  the  overhead 
expenditure  varies  with  different  feeding-stuffs,  all  the  factors  which  tend 
to  obscure  the  net  tissue-building  value  of  a  food  must  be  determined 
separately.  The  factor  of  digestibility  is  easily  measured,  provided  the 
experimental  periods  are  long  enough  and  the  daily  food-supply  is  constant 
enough  to  secure  uniformity  in  the  processes  of  digestion  throughout  the 
extensive,  complicated  digestive  canal.  The  influence  upon  metabolism  of 
the  products  of  digestion  is  not  so  easily  studied,  and  yet,  as  already  seen, 
this  must  be  most  carefully  taken  into  consideration.  A  large  proportion 
of  the  energy  of  food  absorbed  is  expended  simply  in  a  more  active  cell 
metabolism  of  the  animal,  and  it  is  only  that  part  of  the  food  not  expended 
in  this  increment  which  is  of  true  use  for  the  deposition  of  fat,  flesh,  or  milk 
production,  the  main  purposes  of  the  beef-producing  and  dairy  industries. 

The  true  measure  of  this  “overhead”  in  heat-production  which  must  be 
charged  against  the  processes  of  digestion  and  absorption  has  been  sought 
in  various  ways.  The  experimental  method  of  attack  in  studying  the  energy 
value  of  a  food  recognized  that  the  fasting  metabolism  must  be  known,  but 
assumed  it  could  be  computed.  Thus,  anticipating  probable  injury  to  the 
ruminant  as  the  result  of  fasting,  investigators  have  resorted  to  every  other 
expedient  to  secure  evidence  with  regard  to  the  so-called  true  net  available 
energy  of  foodstuffs.  One  method  has  been  to  estimate  the  fasting  katabo- 
lism  from  a  comparison  of  the  metabolism  on  two  different  feed-levels,  the 
observed  difference  in  heat  output  being  accredited  to  the  difference  in 
feed.  The  error  of  this  method  lies  in  the  assumption  that  the  metabolism 
proceeds  as  a  straight-line  function  of  the  ration®  but  there  is  no  evidence 
on  true  fasting  ruminants  thus  far  published  to  support  this  assumption. 
In  view  of  the  enormous  investment  involved  in  beef  and  milk  production, 
and  in  view  of  the  fact  that  heretofore  the  economic  valuation  of  foodstuffs 
has  been  determined  by  the  method  just  outlined,  a  careful  experimental 
investigation  of  the  best  method  for  determining  the  true  value  of  food  to 
the  animal,  i.  e.,  by  actual  fasting,  is  imperative.  Obviously  the  first  step 
in  such  an  experimental  attack  is  to  attempt  to  measure  directly  the  true 
fasting  katabolism  of  ruminants,  and  subsequently  to  use  this  fasting 

°  Armsby  (The  principles  of  animal  nutrition,  New  York,  1906,  2d  ed.,  p.  430)  cites  the  fact  that 
his  experiments  on  timothy  hay  are  the  only  experiments  of  which  he  knew  at  that  time  which 
bear  out  this  point.  Nevertheless,  he  is  inclined  to  think  that  this  assumption  is  true,  although 
he  states  that  “the  evidence  of  so  few  experiments  must  naturally  be  accepted  with  some  re¬ 
serve." 


INTRODUCTION 


11 


katabolism  as  the  standard  for  studying  the  true  effects  of  varying  quantities 
of  individual  feeds. 

The  most  logical  method  would  seem  to  be  to  measure  the  fasting  metabo¬ 
lism  directly  and  then,  by  giving  the  animal  various  quantities  of  food,  to 
study  accurately  the  increase  in  metabolism  due  to  each  of  these  various 
amounts.  Since  the  various  avenues  of  energy-expenditure  play  relatively 
such  an  important  role,  an  estimate  of  the  value  of  any  given  food  must  be 
based  on  definite  knowledge  of  the  extent  to  which  this  food  affects  the 
standard  or  fasting  metabolism.  Does  the  ingestion  of  food  increase  the 
metabolism  above  this  fasting  base-line  in  direct  proportion  to  the  amount 
of  food  ingested?  Is  the  fasting  metabolism  the  same,  irrespective  of  the 
state  of  nutrition  previous  to  fasting?  Is  it  affected  by  environmental  tem¬ 
perature  or  by  water  consumption?  These  problems  suggest  that  if  the 
element  of  uncertainty  introduced  by  attempts  to  establish  the  fasting 
metabolism  through  indirect  methods  could  be  avoided  by  actual  measure¬ 
ment  of  the  fasting  katabolism,  the  whole  complex  problem  of  determining 
the  specific  value  of  various  rations  would  be  placed  upon  a  sounder  basis. 
The  main  object  of  the  research  reported  in  this  monograph,  therefore,  was 
to  throw  positive  light  upon  the  pure  fasting  katabolism  of  large  ruminants, 
and  the  first  problem  was  a  determination  of  the  course  of  the  metabolism 
in  steers  from  the  time  when  the  last  food  is  ingested  until  the  fasting  state 
is  reached. 


OTHER  INVESTIGATIONS  ON  THE  FASTING  OF 

LARGE  ANIMALS 

Several  fasting  experiments  have  been  carried  out  with  large  animals  in 
the  past,  but,  singularly  enough,  these  are  only  rarely  referred  to  in  modem 
literature.  This  may  be  due  to  the  fact  that  some  of  the  investigators  who 
have  worked  with  large  animals  have  published  their  results  in  remote  and 
almost  inaccessible  publications.  The  fasting  of  a  large  animal  (weighing 
400  kg.  or  more)  for  several  days  affords  the  opportunity  for  such  an 
important  study,  however,  that  the  literature  on  the  subject  should  be 
reviewed. 

MAGENDIE,  1852 

The  earliest  instance  of  the  fasting  of  a  large  animal  is  that  reported  by 
Magendie.®  A  9-year  old  mare,  suffering  from  glanders,  was  deprived  of  all 
food,  but  was  allowed  6  liters  of  water  every  24  hours,  which  she  drank  each 
day  until  she  died.  Most  of  the  observations  had  to  deal  with  the  blood, 
samples  of  which  were  taken  frequently.  Magendie  does  not  comment  on 
the  general  appearance  of  the  animal  during  the  first  week  of  fasting.  He 
states  that  on  the  eighth  day  the  mare  did  not  appear  to  have  been  affected 
appreciably  by  the  fast,  for  she  walked  and  ran  about  as  usual.  On  the 
fifteenth  day  her  physical  condition  was  altered  but  slightly,  and  the 
decrease  in  flesh  was  hardly  noticeable.  Indeed,  she  was  inclined  to  run 
about  when  allowed  out  of  the  stable.  On  the  twentieth  day  the  appearance 
of  the  animal  had  altered  greatly.  Her  hair  had  changed  color,  grown 
longer,  and  bristled  like  that  of  a  bear.  She  had  the  appearance  of  being 
blind,  as  the  eyes  had  become  glassy  and  seemed  artificial.  This  change 
took  place  rapidly,  but  otherwise  the  animal  was  unusually  vigorous.  She 
was  allowed  to  run  around  the  stable  yard,  and  upon  hearing  the  crack  of 
a  whip  began  to  run  more  rapidly.  It  was  evident  that  she  could  stand  a 
longer  fast,  although  the  heart-rate  seemed  feeble.  The  animal  died,  after 
24  days  of  complete  abstinence,  except  for  6  liters  of  water  daily.  Magendie 
considered  that  this  experiment  was  only  a  preliminary  trial,  but  that  it 
seemed  to  open  a  new  way  to  study.  He  suggested  that  it  should  be 
repeated,  with  frequent  weighings  of  the  animal,  and  especially  with  records 
of  the  body-temperature.  The  desirability  of  working  on  an  animal  with¬ 
out  glanders  is  also  pointed  out.  It  is  unfortunate  that  Magendie  devoted 
so  much  attention  to  physical  characteristics  and  the  chemistry  of  the 
blood,  for  there  must  have  been  many  other  important  observations  that 
apparently  escaped  record. 

COLIN,  1862  AND  1888 

Although  he  did  not  study  large  ruminants,  such  as  the  steer,  and  made 
no  measurements  of  the  respiratory  exchange,  Colin* * 6  of  Alfort  (almost 

°  Magendie,  Lemons  faites  au  College  de  France,  1851-52;  collected  and  analyzed  by  Faugon- 

neau-Dufresne,  Paris,  1852,  pp.  29  et  seq. 

6  Colin,  Bulletin  Soci6t6  impfiriale  et  centrale  de  M6decine  v6t6rinaire,  1862,  7,  2d  series,  pp. 
194  and  262;  also  Traits  de  Physiologic  Compar£e  des  Animaux,  3d  ed.,  Paris,  1888,  2,  pp.  682 
et  seq. 


OTHER  INVESTIGATIONS  ON  FASTING  OF  LARGE  ANIMALS 


13 


'contemporaneously  with  Grouven;  see  pp.  15  to  20)  reported  the  results 
t>f  several  fasting  experiments  with  horses.  A  healthy,  vigorous,  moderately 
fat  adult  horse,  weighing  405  kg.,  and  with  well-developed  muscles,  went 
without  food  completely  for  30  days  during  the  month  of  July,  but  drank 
water  ad  libitum.  In  30  days  he  drank  but  42  liters,  or  an  average  of  1.4 
liters  per  day.  Daily  records  were  kept  of  the  respiration-rate,  the  heart- 
rate,  and  the  body-temperature.  The  total  loss  in  body-weight  was  80  kg. 
or  6.5  grams  per  kilogram  of  body-weight  per  24  hours.  The  body-tempera¬ 
ture  remained  essentially  unchanged  throughout  the  fast.  Colin  states  that 
he  will  publish  the  details  of  his  temperature  measurements  later,  but 
unfortunately  it  has  been  impossible  to  find  any  such  later  publication. 

On  the  thirtieth  fasting  day,  although  there  was  nothing  to  indicate  that 
the  horse  would  die,  the  animal  was  killed.  The  carcass  gave  the  following 
data: 


kg. 

Body .  325.0 

Blood .  27.0 

Skin  and  hoofs .  16.0 

Bone  and  cartilages .  45.0 

Muscles  and  tendons .  159.0 

Free  fat .  19.7 

Viscera .  25.6 

Gastro-intestinal  matter .  20.2 

Loss .  6.5 


Total .  325.0 


From  this  analysis  Colin  points  out  that  the  emaciation  could  have  pro¬ 
ceeded  as  much  farther  again.  There  was  fat  under  the  skin  near  the  neck 
and  shoulders,  in  the  inguinal  region,  and  on  the  buttocks.  The  fat  in  the 
abdominal  cavity  formed  a  layer  4  to  5  cm.  thick  and  weighed,  together 
with  some  fat  in  the  breast,  14  kg.  Fat  was  also  found  in  the  muscular 
interstices  and  large-sized  globules  of  fat  were  found  in  the  cells  of  the  liver. 

A  small  pony  of  163  kg.  (which  had  a  case  of  glanders)  fasted  for  19 
days  in  November.  He  lost  39  kg.  during  this  time,  or  one-fourth  of  his 
initial  weight  instead  of  one-fifth,  as  in  the  case  of  the  first  horse.  His  daily 
loss  in  weight  was  double  that  of  the  first  animal,  i.  e.,  12.5  grams  per 
kilogram  of  live  weight. 

Another  horse,  weighing  351  kg.,  which  was  slightly  ill,  lost  in  18  days  of 
fasting  89  kg.  Colin  believes  he  lost  more  than  the  pony,  because  he  was 
very  thin,  and  he  lost  twice  as  much  per  day  as  the  horse  which  fasted  for 

one  month. 

Another  horse,  weighing  504  kg.,  lost  65.5  kg.  in  4  days  of  fasting,  that 
is,  20.2  kg.  during  the  first  day,  13.8  kg.  the  second  day,  16  kg.  the  third 
day,  and  15.5  kg.  the  fourth  day.  He  died  on  the  fifth  day,  much  more 
exhausted  than  the  horse  which  lived  for  30  days  without  food.  But  this 
horse  had  glanders,  developed  a  fever,  and  instead  of  using  up  6  grams  per 
kilogram  of  body-weight  daily  he  consumed  32.5  grams  daily,  or  five  times 
as  much  as  the  healthy  horse.  This  is  the  largest  loss  Colin  found  with  any 
of  his  horses  and  a  loss  which  he  thinks  rarely  takes  place.  This  enormous 
“consumption”  is  explained  by  the  febrile  condition.  Colin  points  out  that, 


14 


METABOLISM  OF  THE  FASTING  STEER 


according  to  the  analyses  of  Lassaigne,0  a  horse  at  rest  burned  2,241  grams; 
of  carbon  and  as  a  result  of  exercise  burned  4,887  grams  or  more  than 
double,  and  he  concludes  that  fever  increases  the  expenditure  of  combustible 
body  material  just  as  muscular  exercise  increases  the  expenditure  of  com¬ 
bustible  material  obtained  from  foods.  The  chemical  result  is  the  same  in 
both  cases. 

Still  another  horse,  weighing  193  kg.,  which  had  undergone  a  slight 
surgical  operation,  lost  8.4  kg.  per  24  hours  during  the  first  2  days  of  fasting, 
or  43  grams  per  kilogram  of  body-weight  per  day  instead  of  6.5  grams,  as 
in  the  case  of  the  30-day  fast.  But  this  loss  for  the  first  2  days  was  much 
greater  than  that  of  the  following  days  and  should  not  be  compared  with 
the  average  value  obtained  during  fasts  of  longer  duration. 

Colin  remarks  that  large  ruminants  may  lose  in  the  same  proportion  and 
points  out  that  a  1-year  old  heifer,  weighing  146  kg.,  lost  in  the  first  days 
of  fasting  4.3  kg.  in  24  hours  or  29  grams  per  kilogram  of  body-weight.  It 
is  unfortunate  that  the  details  are  not  given  for  the  daily  loss  in  weight, 
the  water  drunk,  and  the  urine  and  feces  passed,  so  that  the  insensible  loss 
could  be  computed. 

With  the  horse  which  fasted  30  days  a  study  was  made  of  the  urine.  At 
the  beginning  of  the  experiment  the  urine  was  thick,  muddy  with  sediment, 
and  alkaline.  Hydrochloric  acid  brought  about  a  quick  effervescence  and 
later  the  formation  of  crystals  of  hippuric  acid.  But  at  the  end  of  a  few 
days  the  urine  had  changed  in  appearance  and  character,  becoming  clear, 
transparent,  and  acid.  In  fact,  the  urine  had  the  essential  characteristics 
of  the  urine  of  a  carnivorous  animal. 

Colin  points  out  that  it  is  a  well-known  fact  that  carnivora  can  with¬ 
stand  fasting  better  than  herbivora.  They  are  accustomed  to  frequent  fasts 
and  uncertainty  in  the  securing  of  food  and  are  therefore  prepared  naturally 
in  some  way  for  irregularity  in  eating,  an  irregularity  much  less  frequently 
experienced  by  herbivora.  The  digestive  tract  of  carnivora,  which  is  not  so 
large  as  that  of  herbivora,  does  not  suffer  from  the  lack  of  ballast.  One  meal 
supplies  the  carnivorous  animal  with  food  for  a  long  time.  When  food  from 
outside  sources  is  lacking,  food  of  a  similar  nature  is  available  within  the 
carnivorous  animal  itself.  The  origin  of  the  food  alone  changes,  but  the 
kind  of  food  remains  the  same.  When  herbivora  are  subjected  to  fasting, 
however,  the  character  of  alimentation  is  changed,  for  their  own  body-flesh 
must  be  consumed  in  place  of  vegetable  material.  The  herbivorous  animal 
therefore  becomes  carnivorous,  for,  not  being  able  to  derive  any  sugar  or 
starch  from  food  materials,  he  has  to  borrow  from  his  own  flesh  to  make  up 
for  this  lack. 

A  remarkable  fasting  experiment  with  a  rabbit  is  also  reported  by  Colin. 
This  rabbit  fasted  for  37  days  without  either  food  or  water.  His  initial 
weight  was  4,220  grams.  On  the  thirty-seventh  day  he  weighed  1,807  grams, 
or  considerably  less  than  one-half  of  his  initial  body-weight.  This  experi¬ 
ment  is  striking,  since  it  is  the  common  belief  of  investigators  in  animal 
physiology  that  rabbits  withstand  fasting  poorly.  Thus,  experience  with 
rabbits  has  shown  that  after  a  relatively  few  days  of  fasting  there  is  an 

°  Lassaigne,  Journ.  de  Chimie  medicale,  1846,  2,  pp.  477  and  751 ;  ibid.,  1849,  5,  pp.  13  and  253. 


OTHER  INVESTIGATIONS  ON  FASTING  OF  LARGE  ANIMALS 


15 


enormous  increase  in  the  breakdown  of  protein  tissue,  the  so-called  “pre¬ 
mortal  rise”  in  nitrogen  excretion  appears,  and  death  follows  rapidly 
thereafter. 

Colin  established  the  fact  that  young  animals  withstand  fasting  less  suc¬ 
cessfully  than  do  adult  animals,  in  large  part  because  their  deposit  of  fat 
is  much  smaller.  The  influence  of  a  fatty  deposit  was  well  shown  in  the 
case  of  a  goose,  which,  with  an  initial  weight  of  4,800  grams,  lived  for  44 
days  without  food,  although  receiving  water  ad  libitum.  At  the  end  of  this 
time  it  weighed  2,325  grams,  or  less  than  one-half  of  its  initial  body -weight. 
After  death,  446  grams  of  free  fat  were  found  in  the  body. 

Although  the  third  edition  of  Colin’s  treatise  was  issued  as  far  back  as 
in  1888,  his  discussion  of  fasting  animals  may  well  be  recommended  to  all 
workers  in  physiology.  Unfortunately,  data  with  regard  to  large  ruminants 
are  missing  in  his  reports,  but  the  fundamental  principles  underlying  the 
influence  of  fasting  (i.  e.,  the  effect  of  age  and  the  effect  of  a  fatty  deposit) 
were  strikingly  brought  out  in  his  observations  and  his  discussion  of  results. 

GROUVEN,  1864 

Among  the  earlier  researches  in  nutrition  the  work  of  Hubert  Grouven  on 
the  fasting  metabolism  of  cattle  demands  especial  attention,  as  it  precedes 
any  other  similar  investigation  by  nearly  60  years.  Since  his  fundamental 
concepts  of  the  study  of  nutrition  problems  are  recognized  as  sound  and 
essential  to-day,  it  is  unfortunate  that  his  work  has  been  unknown  or  disre¬ 
garded  during  all  these  years  by  writers  on  animal  nutrition.41  Grouven’s 
work  may  be  summarized  under  the  three  separate  phases  in  which  he  made 
notable  contributions,  namely,  his  general  method  of  procedure  and  his 
physiological  and  chemical  studies  of  the  problems  involved.  His  work  is 
quoted  here  in  some  detail  because  of  his  sound  grasp  of  the  essentials 
involved  in  such  studies  and  also  to  remove  the  possible  impression  that 
the  idea  of  subjecting  cattle  to  fasting  as  a  requisite  of  nutrition  studies  is 
of  recent  origin. 

Prior  to  Bischoff  and  Voit,* * * * * 6  of  whose  work  Grouven  made  extensive  use, 
the  nutritive  value  of  a  feed  was  based  simply  on  the  gains  in  live  weight 
that  the  feed  produced  in  the  animal  and  no  particular  attention  was  given 
to  the  character  of  the  gains  or  losses,  the  assumption  being  that  they  repre¬ 
sented  body-tissue.  The  fundamental  incentive  to  Grouven’s  work  lay  in 
his  recognition  of  the  fact  that  great  changes  occur  in  the  gross  live  weight 
of  an  animal  wThich  have  no  bearing  whatsoever  on  changes  in  body-tissue. 
Convinced  that  the  nutritive  value  of  food  must  therefore  be  expressed 
directly  in  terms  of  the  gain  or  loss  of  muscle-tissue  and  fat,  he  studied  the 
problem  from  this  point  of  view,  thus  making  a  radical  departure  from 
previous  methods  of  investigation. 

°  Grouven,  Physiologisch-chemische  Fiitterungsversuche.  Zweiter  Bericht  uber  die  Arbeiten 

der  agrikulturchemischen  Versuchsstation  zu  Salzmunde,  Berlin,  1864.  Unfortunately,  these 

experiments  were  reported  in  a  publication  rarely  found  in  American  libraries,  and  it  is  because 

of  the  inaccessibility  of  these  data  that  we  review  his  report  here  in  somewhat  greater  detail  than 

seems  necessary  in  the  case  of  those  writers  whose  works  are  more  generally  available  and  known. 

6  Bischoff,  Der  Harnstoff  als  Maass  des  StofTwechsels,  Giessen,  1853;  Bischoff  and  Voit,  Die 
Gesetze  der  Ernahrung  des  Fleischfressers  durch  neue  Untersuchungen,  Leipzig  and  Heidel¬ 
berg,  1860. 


16  METABOLISM  OF  THE  FASTING  STEER 

Method  of  ‘procedure — Grouven’s  method  of  attack  involved  a  complete 
physical  and  chemical  study  of  the  contents  of  the  digestive  tract  of  the 
ruminant.  This  study  served  as  a  physiological  basis,  by  means  of  which 
the  relative  effects  of  different  feeds  on  body-tissue  and  on  the  feed  residues 
in  the  alimentary  tract  could  be  determined  separately,  since  both  are  mani¬ 
fested  in  terms  of  live  weight.  He  planned  to  study  the  nutritive  value  of 
numerous  individual  materials  in  a  pure  form,  such  as  sugar,  starch,  and 
dextrine.  He  realized,  however,  that  these  could  not  be  fed  to  a  ruminant 

Table  1. — Live  weight,  water  intake,  and  excreta  of  fasting  oxen,  and  contents  of  digestive 

tract  before  and  after  fasting  ( Grouven ) 


Measurement 

(a) 

Average 

for 

2  cows 

Brown  ox 

Black  ox 

(f) 

Average 

for 

2  oxen 
(5  +d)  +2 

( b ) 

After 

fasting 

5  days 

(c) 

Loss 

(a~b) 

id) 

After 

fasting 

8  days 

(e) 

Loss 

(o-d) 

Live  weight: 

kg. 

kg. 

kg. 

kg. 

kg. 

kg. 

Start  of  fast . 

398 

420 

522 

471 

End  of  fast . 

381 

480 

431 

Loss . 

38  7 

42 

40.4 

Water  intake . 

14.3 

35.4 

24.9 

Urine . 

29  2 

26  7 

27.9 

Feces . 

15  9 

17.2 

16.6 

Contents  digestive  tract  (fill): 

Water . 

52.76 

38.61 

14.15 

66  06 

Dry  matter — 

C . 

4.217 

0  976 

3  241 

1  097 

3.120 

H . 

0  549 

0  128 

0  421 

0.139 

0.410 

O . 

3  527 

0  818 

2  709 

0  921 

2.606 

N . 

0  131 

0  036 

0.095 

0  053 

0.078 

Ash . 

0.969 

0.439 

0.530 

0.584 

0.385 

Total  dry  matter . 

9  393 

2  397 

6  996 

2  794 

6  599 

Total  fill . 

62.15 

41  01 

21 . 14 

68  85 

54.93 

Fat . 

0.287 

0  045 

0.242 

0.048 

0.239 

Cellulose . 

3  007 

0  717 

2.290 

0  694 

2.313 

Water  (per  cent) . 

85 

94 

96 

without  roughage  or  bulk,  as  such  a  feed  alone  would  upset  digestion. 
Accordingly  he  decided  that  the  nutritive  effects  of  a  standard  roughage, 
such  as  rye  straw,  must  first  be  determined.  Then  straw,  plus  a  definite 
amount  of  the  special  purified  food  material,  was  to  be  fed.  To  establish 
the  influence  of  a  basal  ration  of  roughage,  such  as  rye  straw,  he  reasoned 
that  the  fundamental  starting-point  or  base-line  would  be  represented  by 
the  fasting  state  only,  i.  e.,  when  no  food  is  present  to  stimulate  the 
metabolism.  Thus,  he  made  his  greatest  contributions  in  the  execution  of  an 
experimental  plan  based  on  this  conception,  i.  e.,  the  necessity  of  establishing 
a  base-line  as  a  preliminary  to  subsequent  investigations.  Grouven  began 
his  first  experiment  in  1862,  with  2  oxen  and  2  cows,  feeding  each  of  them 
with  a  basal  ration  of  3.5  kg.  of  rye  straw  for  a  period  of  2  weeks.  He 
assumed  that  by  the  end  of  that  time  any  undigested  residues  from  previous 
feed  would  have  been  eliminated  and  that  the  fill  or  residues  in  the 


OTHER  INVESTIGATIONS  ON  FASTING  OF  LARGE  ANIMALS 


17 


alimentary  tract  would  have  a  constancy  characteristic  of  the  daily  ration, 
1  e.,  that  it  would  be  the  same  in  all  four  animals.  The  water  intake  was 
likewise  controlled,  but  only  during  the  last  four  days,  when  each  animal 
was  allowed  7.5  kg.  daily.  The  oxen  then  fasted,  one  for  5  days  and  the 
other  for  8  days.  The  cows,  on  the  other  hand,  were  slaughtered  and  a 
careful  analysis  was  made  of  the  quantity  and  character  of  the  contents  of 
the  alimentary  tract.  The  oxen  were  slaughtered  at  the  end  of  their 
respective  fasts  and  similar  analyses  were  made. 

Physiological  considerations — By  this  experiment  Grouven  contributed 
the  first  physiological  data  showing  the  effect  which  quantitative  changes 
in  feed  produce  on  the  character  and  the  amount  of  fill.  Assuming  that  the 
contents  of  the  digestive  tract  of  the  two  oxen  would  be  the  same  at  the 
beginning  of  the  fast  as  that  of  the  two  cows  which  were  slaughtered  at  that 
time  (all  four  animals  having  received  identical  amounts  of  rye  straw  and 
water) ,  he  calculated  the  amount  of  material  disappearing  from  the  digestive 
tract  during  the  fast  by  deducting  the  amount  found  at  the  end  of  fasting 
from  the  amount  present  at  the  start,  and  from  this  he  determined  the 
amount  assimilated  from  the  straw  during  the  fast,  as  shown  in  Table  1. 
Grouven’s  data  bring  out  some  significant  physiological  facts  regarding  fill, 
or  the  feed  residues  in  the  alimentary  tract.  Practically  nothing  definite 
was  on  record  at  that  time  regarding  the  total  amount  of  fill  in  cattle,  and 
information  regarding  the  effect  of  changes  in  feed  on  fill  was  equally 
lacking.  The  values  for  total  fill,  which  he  records  for  his  cows  (not  fasting) , 
correspond  closely  to  the  figures  obtained  by  Moulton  about  50  years  later. 
His  analysis  of  the  quantitative  changes  in  fill  that  occur  in  different  parts 
of  the  digestive  tract  throws  new  light  on  the  course  of  absorption,  as  indi¬ 
cated  by  the  data  in  Table  2.  The  fact  that  the  quantitative  change  during 


Table  2. — Influence  of  fasting  upon  the  contents  of  the  digestive  tract  of  oxen  ( Grouven ) 


Contents  of — 

Average  for 

2  cows 
(not  fasting) 

Ox 

(5-day  fast) 

Ox 

(8-day  fast) 

Average  for 

2  oxen 

Kg. 

P.  ct.  of 
live 
weight 

Kg. 

P.  ct.  of 
live 
weight 

Kg. 

P.  ct.  of 
live 
weight 

Kg. 

P.  ct.  of 
live 
weight 

Stomach  and  paunch .... 

48.3 

12.1 

34.9 

9.1 

59.4 

12.4 

47.1 

10.8 

Small  intestine . 

5.5 

1.4 

3.3 

0.9 

5.0 

1.0 

4.1 

0.9 

Large  intestine . 

8.5 

2.1 

2.9 

0.8 

4.5 

0.9 

3.7 

0.8 

fasting  is  least  in  the  stomach  and  paunch  and  greatest  in  the  large  intestine 
suggests  that  the  excess  moisture  in  the  fill  was  largely  absorbed  before  the 
fill  was  voided.  This  finding  offers  an  explanation  for  the  occurrence  of 
exceedingly  dry  feces  in  our  own  fasting  and  submaintenance  experiments. 
One  of  the  outstanding  features  shown  by  Grouven’s  data  is  the  great 
increase  in  the  moisture  content  of  fill  in  the  fasting  animal,  which  tends  to 
offset  the  loss  in  dry  matter.  A  further  point  of  significance  is  the  fact  that 
although  identical  amounts  of  rye  straw  and  water  were  consumed  by  the 


18 


METABOLISM  OF  THE  FASTING  STEER 


two  oxen  previous  to  fasting,  the  difference  in  their  fill  at  the  end  of  fasting!* 
amounted  to  about  70  per  cent,  due  in  a  large  measure  to  the  difference  in 
water  consumed  during  the  fast.  In  other  words,  the  assumed  constancy  of 
the  conditions  affecting  live  weight,  on  which  he  based  many  of  his  subse¬ 
quent  calculations,  was  not  materialized. 

Fasting  metabolism — From  the  decrease  in  the  fecal  excretion  during  the 
fasts  and  the  analysis  of  the  fill  at  slaughter,  Grouven  concluded  that  com¬ 
plete  fasting  began  on  the  fifth  day.  The  results  of  his  experiments  with 
5  oxen  are  given  in  Table  3.  Since  the  loss  of  muscle-tissue  was  computed 
from  the  urinary  nitrogen  in  the  usual  manner,  the  nitrogen  requirement  of 
about  50  to  60  grams  daily  (equal  to  from  1.5  to  1.8  kg.  of  body-flesh)  noted 
on  the  fifth  day  without  food,  apparently  represented  the  true  basal  nitrogen 
requirement  during  fasting  in  his  experiments.  Grouven  reasoned  that 
during  fasting  the  flesh  and  fat  metabolism  of  the  animal  would  be  depressed 
to  a  minimum  level,  which  would  not  be  difficult  to  recognize  because  of  its 
constancy.  Moreover,  he  believed  that  the  heat-production  calculated  from 
the  loss  of  flesh  and  fat  under  this  condition  of  minimum  use  would  also 
be  the  same  in  all  those  experimental  conditions  in  which  the  animals  would 
be  given  rations  somewhat  below  maintenance,  and  that  they  would  there¬ 
fore  have  to  supplement  the  ration  with  fat  and  flesh  from  their  own  bodies. 
His  determination  of  the  fat  metabolism  during  fasting  appears  somewhat 
vitiated,  because  of  his  computation  of  the  probable  loss  of  body-fat  from 
changes  in  live  weight  by  using  Voit’s  equations,  the  weakness  of  which  he 
recognized.  His  attempt,  however,  to  correct  the  defect  due  to  dependence 
on  live  weight  by  a  careful  analysis  of  the  different  factors  that  collectively 
must  represent  the  changes  in  gross  live  weight,  that  is,  the  insensible  per¬ 
spiration,  represents  a  real  contribution  to  the  study  of  nutrition  problems. 

Table  3. — Data  for  insensible  loss,  respiratory  exchange,  and  heat-production,  as  derived  from 

metabolism  equations  ( Grouven ) 


Total  loss  in — 

Per  24  hours 

Heat  produced 
per  24  hours 

Ox 

Days 

fast¬ 

ing 

Average 

body- 

weight1 

Flesh 

Fatty 

tissue 

Insen¬ 

sible 

loss 

Car¬ 

bon 

diox¬ 

ide 

pro¬ 

duc¬ 

tion 

Oxy¬ 

gen 

con¬ 

sump¬ 

tion 

Res¬ 

pira¬ 

tory 

quo¬ 

tient 

Total 

Net* 

Black . 

8 

kg. 

501 

kg. 

9.74 

kg. 

11.84 

kg. 

4.19 

kg. 

4.66 

kg. 

4.50 

0.75 

cal. 

314,850 

cal. 

3 13,325 

Brown . 

5 

403 

5.21 

4.99 

1.56 

3.79 

3.52 

.78 

11,620 

13,540 

Ox  I  (1861). . 

3 

431 

2.32 

3.33 

7.16 

4.70 

4.31 

.79 

14,225 

12,995 

Ox  I  (1862). . 

4 

521 

3.16 

5.48 

3.17 

4.79 

4.62 

.75 

15,245 

13,230 

Ox  III  (1861) 

3 

523 

4.43 

3.38 

4.45 

4.99 

4.57 

.79 

15,065 

13,550 

1  Average  of  initial  and  end  weights. 

s  Reduced  to  uniform  conditions  of  450  kg.  body-weight,  15°  C.,  and  3.5  kg.  vaporized  water. 
3  Our  computation  of  Grouven’s  data  gives  values  slightly  different  from  these. 


OTHER  INVESTIGATIONS  ON  FASTING  OF  LARGE  ANIMALS 


19 


Insensible  perspiration — Grouven’s  critical  determination  of  the  water 
blalance  by  means  of  Voit’s  so-called  “control  calculations,”  based,  however, 
on  his  own  analysis  of  the  fill  of  slaughtered  animals,  represents  up  to  the 
present  the  only  attempt  on  record  (except  our  own  data)  to  measure  in 
ruminants  the  daily  insensible  losses  (in  large  part  water-vapor)  through 
the  lungs  and  skin.  This  attempt  recognized  the  great  role  which  water 
plays  in  the  variations  in  live  weight,  and  also  points  out  the  possibilities 
of  the  insensible  perspiration  serving  directly  as  a  measure  of  metabolism. 
In  other  words,  having  determined  the  water  intake,  the  water  voided  in 
feces  and  urine,  and  the  resident  water  in  the  digestive  tract  before  and 
after  fasting,  Grouven  determined  the  amount  and  the  constancy  of  the 
water  lost  in  vaporized  form  as  perspiration.  He  pointed  out  that  this 
so-called  “insensible  perspiration,”  or  invisible  daily  deficit,  is  always  con¬ 
sistent  on  a  given  feed-level  and  represents  an  invisible  loss  which  pre¬ 
sumably  can  find  no  other  means  of  escape  except  through  the  lungs  and 
skin.  The  source  of  this  particular  loss,  as  Grouven  points  out,  is  derived 
from  the  loss  of  muscle  or  fatty  tissue  and  of  Water  preexisting  in  the  body. 
The  direct  form  in  which  it  is  lost  is  largely  water-vapor  and  gaseous 
products.  He  assumes,  therefore,  that  the  insensible  perspiration  represents 
purely  the  by-products  of  tissue  katabolism  and  not  carbon  dioxide  from 
the  process  of  tissue  replacement.  Hence  he  considers  differences  in  the 
amount  of  water  perspired  by  different  animals  as  the  result  rather  than  as 
the  cause  of  differences  in  heat-production. 

Chemical  problems — Based  on  his  exhaustive  chemical  studies  of  the  fill, 
Grouven  concluded  that  none  of  the  carbohydrates  are  absorbed  unchanged 
into  the  blood  and  directly  contribute  to  the  nutritive  processes,  but  that 
they  are  entirely  assimilated  in  the  form  of  fatty  acids  and  glycerides, 
which  are  formed  only  in  the  presence  of  alkaline  solutions,  i.  e.,  primarily 
in  the  small  intestine.  This  revolutionary  theory  regarding  the  path  of  the 
absorption  of  carbohydrates  is,  as  a  matter  of  fact,  wholly  unrecognized 
even  to-day,  save  for  a  reference  to  it  by  Zuntz.0  There  is  considerable  evi¬ 
dence  in  more  recent  investigations  supporting  this  theory.  Although  the 
isodynamic  law  of  replacement  had  not  been  established  at  that  time, 
Grouven  found  that  the  consumption  of  protein  was  smaller  when  rye  straw 
was  fed  than  during  complete  fasting,  thus  forecasting  the  possibility  that 
fat  and  carbohydrates  (for  amount  absorbed  see  Table  1)  may  protect  body 
protein. 

Conclusion — In  view  of  the  comprehensive  basis  upon  wrhich  Grouven’s 
work  was  planned  and  the  extreme  care  with  which  it  was  carried  out,  and 
in  view,  furthermore,  of  the  fact  that  his  whole  work  was  finally  computed 
by  means  of  Voit’s  metabolism  equations  based  on  live  weight,  probably  his 
most  noteworthy  permanent  contribution  is  made  in  his  own  summary  state¬ 
ment,  which  follows  a  discussion  of  the  uselessness  of  accepting  live-weight 
records  at  the  beginning  and  end  of  a  test  as  a  measure  of  the  effect  of  any 
given  food. 

“The  indisputable  fact  remains  that  it  would  never  become  possible  to 
explain  the  results  of  experimental  feeding  on  the  basis  of  scientific  facts 


Zuntz,  Internat.  Agrartechnische  Rundschau,  1914,  S,  Heft  4. 


20 


METABOLISM  OF  THE  FASTING  STEER 


or  to  apply  the  results  of  experimental  feeding  successfully  to  general  prac¬ 
tice  without  a  knowledge  of  the  effect  of  food  on  the  metabolic  exchanges 
which  take  place  in  muscle-tissue,  fat,  water,  and  mineral  salts,  a  knowledge 
which  can  be  obtained  only  by  means  of  a  respiration  apparatus  and 
metabolic  balances.” 

The  potency  of  this  statement,  which  amounts  practically  to  an  acknowl¬ 
edgment  of  weakness  of  his  own  metabolism  measurements,  lies  in  the 
extraordinary  thoroughness  in  detail  with  which  his  experiment  was  planned 
and  carried  out. 


IGNATIEF,  1883 

Ignatief,  in  1883,  studied  the  influence  of  fasting  upon  the  body-weights 
of  steers.0  Thus,  85  steers,  which  were  being  transported  from  Karlovka  to 
Moscow  and  thence  to  St.  Petersburg,  were  divided  into  three  groups.  One 
group  received  food  and  water,  the  second  water  only,  and  the  third  neither 
food  nor  water.  The  animals  were  weighed  just  prior  to  transportation, 
were  weighed  again  at  Moscow,  when  they  had  been  in  the  cattle  cars  for 
6  days,  and  again  at  St.  Petersburg,  3  days  later.  A  comparison  of  the 
average  loss  in  body-weight  of  the  different  groups,  on  the  percentage  basis, 
is  given  in  Table  4.  The  actual  body-weights  are  not  recorded  by  Ignatief. 


Table  4. — Percentage  loss  in  body-weight  of  steers  during  9  days  of  partial  or  complete 

fasting  ( Ignatief ) 


Food  condition 

Percentage  loss  in  body-weight 

First  6  days 

Last  3  days 

Total  for  9  days 

Food  and  water . 

3.11 

5.6 

8.71 

Water  only . 

3.67 

6.2 

9.87 

No  food  or  water . 

9.16 

3.8 

12.98 

Ignatief  points  out  that  the  fasting  steers  which  received  water  lost  less 
weight  than  those  that  received  neither  water  nor  food,  and  probably  would 
have  lived  longer  if  the  fasting  had  been  continued  until  death.  He  states, 
however,  that  water  is  favorable  during  fasting  only  for  steers  and,  to  a 
certain  extent,  rabbits,  but  for  other  animals  water  during  fasting  is  some¬ 
times  harmful.  Evidently  no  records  other  than  body-weights  were  obtained 
by  Ignatief. 

MEISSL,  1886,  AND  TANGL,  1912 

Although  our  report  deals  primarily  with  the  effect  of  fasting  on  rumi¬ 
nants,  brief  mention  is  justifiable  here  of  the  fasting  studies  with  large  swine 
carried  out  by  Meissl  and  Tangl.  In  1886,  Meissl,6  working  at  the  agri¬ 
cultural  experiment  station  at  Vienna,  published  the  results  of  one  3-day 


“  Reported  by  Pashutin,  General  and  Experimental  Pathology  (Pathological  Physiology),  St. 
Petersburg,  1902,  2,  Part  1,  p.  156.  English  translation  of  Pashutin’s  book  is  on  file  in  the 
Nutrition  Laboratory. 

b  Meissl,  Zeitschr.  f.  Biol.,  1886,  22,  p.  104. 


OTHER  INVESTIGATIONS  ON  FASTING  OF  LARGE  ANIMALS 


21 


) 


f&st  with  a  male  hog  weighing  144  kg.  and  one  5-day  fast  with  a  male  hog 
weighing  122  kg.  A  respiration  chamber  employing  the  Pettenkofer  prin¬ 
ciple  was  used,  and  measurements  of  the  carbon-dioxide  production  were 
made.  Later,  in  1912,  Tangl0  subjected  4  male  swine,  two  7  months  old 
(40  to  50  kg.)  and  two  l1/^  years  old  (110  to  120  kg.),  to  fasts  lasting  from 
5  to  9  days.  During  this  time  the  carbon-dioxide  production,  the  production 
of  water- vapor,  and  the  nitrogen,  carbon,  and  energy  in  urine  were  deter¬ 
mined  at  definite  intervals.  The  respiration  chamber  for  average-sized 
animals  at  the  experiment  station  for  animal  physiology  at  Budapest  was 
employed,  an  apparatus  which  combines  the  principles  of  the  Pettenkofer- 
Voit,  Atwater-Benedict,  and  Tigerstedt  respiration  chambers.  The  influ¬ 
ence  of  environmental  temperature  upon  the  carbon-dioxide  production  was 
one  of  the  factors  studied. 

CAPSTICK  AND  WOOD,  1922 

The  heat-production  of  a  male  hog  was  measured  in  the  calorimeter 
described  by  Capstick* * 6  during  six  fasts,  each  of  from  4  to  6  days  in  duration, 
at  environmental  temperatures  ranging  from  10°  to  20°  C.c  The  obser¬ 
vations  extended  over  a  period  of  114  days.  The  hog  was  10  months  old  at 
the  beginning  and  weighed  100  kg. ;  at  the  end  he  weighed  155  kg.  During 
the  feeding-periods  (usually  about  2  weeks  long)  between  the  fasts  the  food 
was  of  the  same  general  character,  but  was  increased  gradually  so  as  to  be 
roughly  proportional  to  the  two-thirds  power  of  the  animal’s  weight.  The 
hog  received  7.5  liters  of  water  daily  while  fasting.  Readings  of  the  various 
instruments  were  taken  at  hourly  or  at  half-hourly  intervals,  when  the 
galvanometer  curve  showed  that  the  hog  was  asleep.  At  the  conclusion  of 
the  experiment  the  curve  and  the  readings  were  carefully  studied,  to  find 
the  times  at  which  the  metabolism  was  at  a  steady  minimum.  Considering 
the  variation  in  the  age  and  weight  of  the  animal  during  the  period  of 
observation  and  the  range  of  temperature  in  the  different  experiments,  the 
authors  conclude  that  the  rate  of  change  6f  the  resting  metabolism  at  any 
moment  depends  only  on  the  time  elapsed  since  the  last  meal  and  is  inde¬ 
pendent  of  the  age  and  weight  of  the  hog  and  the  temperature  of  his  sur¬ 
roundings.  The  data  show  that  the  basal  metabolism  of  the  hog  was  not 
reached  until  the  fourth  day  of  fasting.  The  results  of  these  same  experi¬ 
ments  were  used  by  Capstick  and  Wood  later'*  as  the  basis  for  a  study  of  the 
effect  of  change  in  temperature  on  basal  metabolism.  The  critical  tem¬ 
perature  of  the  hog  was  found  to  be  21°  C.  At  this  temperature  the  basal 
metabolism  was  minimum  and  amounted  to  2,160  calories  in  24  hours,  when 
he  was  420  days  old  and  weighed  136  kg.  This  corresponds  to  904  calories 
per  square  meter  of  body-surface  per  24  hours.  As  the  environmental  tem¬ 
perature  decreased  below  the  critical  temperature,  the  basal  metabolism 
increased  at  the  rate  of  about  4  per  cent  per  degree  Centigrade,  which  corre¬ 
sponds  to  an  increase  of  approximately  40  per  cent  for  a  temperature  differ¬ 
ence  of  10°  C.  (commonly  found  between  summer  and  winter  conditions). 

_ 

°  Tangl,  Biochem.  Zeitschr.,  1912,  44,  pp.  235  and  252. 

6  Capstick,  Journ.  Agric.  Sci.,  1921,  11,  p.  408. 

‘Capstick  and  Wood,  Proc.  Roy.  Soc.  London,  Ser.  B,  1922,  94,  p.  35. 

d Capstick  and  Wood,  Journ.  Agric.  Sci.,  1922,  12,  p.  257. 


22 


METABOLISM  OF  THE  FASTING  STEER 


If  the  same  law  holds  in  the  case  of  a  steer,  whose  basal  metabolism  at  1^° 
C.,  or  summer  temperature,  is  6,000  calories,  his  basal  metabolism  at  8° 
in  an  open  yard  in  winter  would  be  9,000  calories.  It  is  suggested  that  the 
increase  of  3,000  calories  is  met  by  the  utilization  of  the  thermic  energy  of 
the  coarse  fodder  included  in  the  ration. 

DEIGHTON,  1923 

Employing  the  calorimeter  for  large  animals  (devised  by  A.  V.  and  A.  M. 
Hill  and  improved  by  J.  W.  Capstick)  at  the  Cambridge  School  of  Agri¬ 
culture,  England,  Deighton0  studied  the  metabolism  of  a  pig  while  fasting, 
at  various  ages  from  75  days  to  about  l1/^  years.  The  fasting  was  in  some 
instances  prolonged  to  104,  109,  and  even  116  hours.  The  pig  weighed 
12.7  kg.  at  the  start  of  the  experimental  season,  when  75  days  old,  and 
137.4  kg.  at  the  end  of  the  season,  when  483  days  old,  and  fasted  on  12  differ¬ 
ent  occasions.  The  author  in  this  really  excellent  research  concludes  that 
in  the  pig,  as  in  human  beings,  the  metabolism  per  unit  of  surface  area  is 
greater  in  mid-youth  than  at  any  other  time  of  life,  a  fact  which  is  directly 
ascribable  to  growth.  The  metabolism  following  the  ingestion  of  food 
reached  its  maximum  after  5  hours  and  then  declined. 

ARMSBY  AND  BRAMAN,  1923-24 

An  abstract  of  results  on  fasting  experiments  with  2  cows,  carried  out 
under  the  direction  of  Professor  H.  P.  Armsby,  of  the  Institute  of  Animal 
Nutrition  at  State  College,  Pennsylvania,  was  reported  by  us  in  our  first 
monograph.* * * 6  The  details  of  these  experiments  had  not  been  published  by 


Table  5. — Carbon-dixoide,  heat,  and  methane  production  of  fasting  cows  ( Braman ) 


Cow 

Time  without  feed 

Produced  per  24  hours 

Carbon 

dioxide 

Heat 

Methane 

am. 

cal. 

am. 

886  IV 

24  to  48  hours . 

2,223 

6,743 

27.4 

886  IV 

48  to  72  hours . 

1,987 

6,328 

11.8 

885  IV 

24  to  48  hours . 

2,247 

6,750 

33.5 

885  IV 

48  to  72  hours . 

2,148 

6,557 

17.4 

885  III 

5  days1 . 

2,034 

6,577 

5.8 

887  III 

9  days1 . 

1,885 

6,061 

2.8 

874  III 

9  days1 . 

2,091 

6,302 

4.1 

1  The  values  given  for  cow  885  III  represent  an  average  for  the  fourth  and  fifth  days  of  fasting ;  ! 
those  for  cows  887  III  and  874  III  represent  averages  for  the  eighth  and  ninth  fasting  days. 


Professor  Armsby  at  that  time,  but  permission  was  given  us  by  him  to  cite  j 
his  findings.  In  1924,  following  Professor  Armsby ’s  death,  Braman0  reported 
the  results  of  fasting  experiments  with  5  cows,  including  revised  figures  for  | 

°  Deighton,  Proc.  Royal  Soc.,  London,  1923,  Series  B,  95,  p.  340;  apparatus  described  by  A.  V. 

and  A.  M.  Hill,  Journ.  Physiol.,  1914,  48,  p.  xiii,  and  later  by  Capstick,  Journ.  Agric.  Sci.,  1921, 

11,  p.  408. 

6  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  Table  66,  p.  256. 

e  Braman,  Journ.  Biol.  Chem.,  1924,  60,  p.  79. 


OTHER  INVESTIGATIONS  ON  FASTING  OF  LARGE  ANIMALS  23 

the  two  earlier  experiments  which  Professor  Armsby  had  privileged  us  to 
cate.  Braman’s  data  are  summarized  in  Table  5. 

These  experiments  were  carried  out  to  furnish  additional  data  on  the 
ratio  of  carbon-dioxide  to  heat-production  in  cattle,  concerning  which  an 
earlier  report®  had  been  published  in  1920,  dealing,  however,  only  with 
cattle  on  feed.  As  a  result  of  these  fasting  experiments  and  other  experi¬ 
ments  with  very  low  feed  intake  new  equations  were  derived,  which,  Braman 
states,  confirm  the  previous  conclusion: 

“The  amounts  of  carbon  dioxide  and  heat  produced  are  approximately 
linear  functions  of  the  feed.  ...  As  the  feed  increases  the  amount  of  heat 
produced  does  not  increase  as  rapidly  as  the  amount  of  carbon  dioxide 
produced.  In  other  words,  the  ratio  of  carbon  dioxide  to  heat  has  its  maxi¬ 
mum  in  fasting,  and  decreases  quite  regularly,  but  slowly,  with  increase  in 
feed.  This  gradual  change  in  the  relation  of  the  amount  of  carbon  dioxide 
and  heat  produced  is  caused  by  variation  in  the  proportion  of  the  kinds  of 
nutriment,  from  the  ration  and  from  the  body,  which  are  metabolized.”6 


°  Armsby,  Fries,  and  Braman,  Proc.  Nat.  Acad.  Sci.,  1920,  6,  p.  263. 
b  Braman,  Journ.  Biol.  Chem.,  1924,  60,  p.  88. 


I 

\ 

\ 

I 

l 

CHANGES  IN  APPARATUS  AND  TECHNIQUE  j 

Our  research  was  carried  out  with  the  equipment  as  described  in  our 
earlier  monograph.®  Certain  significant  modifications  and  additions  made 
since  that  time  need  special  consideration  and  recording  here. 

CHANGES  IN  THE  LABORATORY  BUILDING 

Arrangement  of  laboratory  rooms — The  general  floor  plan  of  the  labora¬ 
tory  fgr  animal  nutrition  is  shown  in  Fig.  1.  The  main  floor  is  divided  into 
four  rooms.  The  room  on  the  right  contains  the  respiration  chamber  A,  the 
Bullock  scales  M,  and  the  water  tub  N.  Adjoining  this,  but  separated  by  a 
double  wall,  is  a  small  room  containing  the  aliquoting  table  B  and  the 


Respiration  chamber  A,  with  feed-box  a,  feed-chute  b,  water-trough  c,  and  feces  grid  d;  B,  ali¬ 
quoting  table;  C,  blower  delivering  outdoor  air  into  chamber;  D,  table  holding  balance  for 
weighing  absorber  bottles;  E,  bench  containing  several  gas-analysis  apparatus;  F,  pipe 
delivering  samples  of  air  from  aliquoting  table  to  gas-analysis  apparatus ;  G,  G,  tubes  through 
which  samples  of  outdoor  air  are  drawn  for  control  tests  of  the  gas-analysis  apparatus;  H,  H, 
metabolism  stalls  with  urine  tubes  in  center;  K,  K,  feed-boxes;  L,  L,  feces  traps;  M,  scales 
for  weighing  steers;  N,  water-tub;  O,  stairway  to  basement;  R,  R,  R,  R,  radiators;  S,  sink; 
T,  switchboard;  U,  shelves  and  closets  for  supplies;  W,  W,  tables. 

balance  D,  for  weighing  the  soda-lime  and  Williams  bottles.  The  long, 
narrow  room  to  the  left  of  this,  on  the  front  of  the  building,  contains  the 
gas-analysis  apparatus  on  the  bench  E,  the  switch  board  T,  and  shelves  and 
storage  facilities  U.  The  large  room  back  of  this  contains  the  two  metabo¬ 
lism  stalls,  showing  feed  boxes  K,  K,  the  traps  for  feces  L,  L,  and  the  holes 
H,  H,  through  the  floor  for  insertion  of  urine  tubes. 

•  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923. 

24 


CHANGES  IN  APPARATUS  AND  TECHNIQUE 


25 


, Control  of  environmental  temperature — The  importance  of  studying  the 
influence  of  environmental  temperature  made  necessary  facilities  for  a 
reasonably  exact  control  of  the  temperature  in  the  metabolism  stalls  and  in 
the  respiration  chamber.  These  facilities  are  supplied  by  an  adequate 
steam  radiation,  whereby  a  temperature  of  not  less  than  30°  C.  can  be 
maintained  even  during  the  coldest  weather,  and  by  five  windows  and  three 
doors,  the  opening  of  which  will  bring  about  a  reduction  of  the  temperature 
to  a  point  closely  approximating  the  outdoor  temperature.  When  the  cham¬ 
ber  was  installed  in  this  building,  space  was  provided  on  all  four  sides  for 
free  circulation  of  air.  The  room  containing  the  respiration  chamber  can 
be  shut  off  from  the  room  containing  the  metabolism  stalls  by  double  doors, 
and  it  is  thus  possible  to  maintain  entirely  unlike  temperature  conditions 
in  the  two  rooms,  if  desired.  In  lieu  of  a  much  preferred  automatic  control, 
this  type  of  temperature  control  served  reasonably  well.  Owing  to  the  wide 
range  of  climatic  conditions  in  America,  this  temperature  control  is  a  very 
important  factor  in  the  study  of  the  effect  of  variations  in  environmental 
temperature  upon  the  metabolism  of  beef  animals.  Unfortunately,  with  the 
forms  of  respiration  calorimeter  thus  far  devised,  the  environmental  tem¬ 
perature  can  be  altered  within  only  a  few  degrees,  and  it  would  seem  as  if 
this  problem  must  be  attacked  by  means  of  respiration  chambers  in  which 
the  temperature  of  the  air  can  be  greatly  altered,  or  else  a  new  type  of 
calorimeter  must  be  devised  to  meet  this  important  condition. 

Motor-generator  set — Although  an  alternating  current  can  for  the  most 
part  be  used  as  well  as  a  direct  current,  if  a  number  of  magnets  are  employed 
a  direct  current  is  necessary,  particularly  in  the  regulation  of  the  electrical 
by-pass.  The  entire  equipment  at  Durham  has  therefore  been  arranged 
with  motors  requiring  a  direct  current.  The  regular  commercial  110-volt 
alternating  current  drives  a  motor  connected  to  a  direct-current  generator 
(110-volt)  by  a  single  shaft.  The  motor-generator  set  is  installed  in  the 
basement  of  the  laboratory.  Although  it  is  believed  that  a  direct  current 
is  most  advantageous  for  the  working  of  the  apparatus  as  a  whole,  it  is 
always  possible  to  arrange  for  the  actuation  of  the  several  magnets  by 
storage  batteries  and  to  use  an  alternating  current  for  the  motors. 

Provision  for  Collection  of  Individual  Urinations 

The  method  of  collecting  the  urine  by  attaching  an  ordinary  urine  funnel 
to  the  animal  and  passing  the  outlet  tube  through  the  floor  of  the  metabolism 
stall  to  receptacles  below  has  been  described  in  an  earlier  report.0  The 
receptacles  commonly  used  are  5-gallon  carboys,  each  of  which  rests  per¬ 
manently  on  the  balance  of  a  scale.  Since  in  many  experiments,  particularly 
in  fasting,  it  is  essential  to  know  the  time  when  the  urine  is  voided,  as  well 
as  the  quantity,  a  simple  electrical  contact  was  installed  by  which  a  bell  is 
rung  when  a  fresh  flow  of  urine  passes  and  raises  the  balance-arm  of  the 
scale.  This  bell  continues  to  ring  until  the  carboy  is  again  exactly  counter¬ 
poised  and  the  contact  on  the  balance-arm  broken.  By  this  means  it  is 
possible  to  record  not  only  the  exact  moment  of  each  urination,  but  likewise 
the  exact  weight  of  the  urine  voided.  The  scales,  which  are  also  used  for 


°  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  pp.  28  and  32. 


26 


METABOLISM  OF  THE  FASTING  STEER 


weighing  feces,  are  the  so-called  “silk  scales,”  weighing  to  125  kg.  The 
beam  has  10-gram  graduations  for  a  beam  range  of  2  kg. 

ADDITIONS  TO  RESPIRATION  CHAMBER 

The  respiration  chamber,  as  originally  designed  and  used,  had  no  pro¬ 
visions  for  feeding  and  watering  or  for  the  collection  of  urine  and  feces, 
since  it  was  planned  primarily  for  short  2-hour  experiments.  Even  during 
the  long  fasts  of  5  to  14  days  the  respiration  experiments  were  only  of  2 
hours’  duration.  It  was  considered  desirable,  however,  to  have  a  complete 
record  of  all  excreta  voided  during  these  fasts,  and  the  first  change  in  the 
chamber  was  therefore  made  to  provide  for  the  collection  of  excreta  while 
the  animal  was  inside  the  chamber.  On  the  basis  of  the  gratifying  results 
obtained  during  the  continuous  3-day  experiments  in  April  and  May  1924, 
it  was  decided  to  lengthen  the  experiments  from  2  to  24  hours  or  to  several 
continuous  24-hour  periods.  Furthermore,  it  was  found  highly  desirable  to 


Fig.  2. — Feed-chute,  feed-box,  feces-chute,  and  provision  for  collection 
of  urine  in  respiration  chamber 


be  able  to  run  experiments  in  which  the  animal  could  be  fed  and  watered  as 
usual  for  a  day  or  more,  and  then  be  subjected  to  fasting,  in  order  to  observe 
on  succeeding  days  the  influence  of  food  on  the  one  hand  and  the  withhold¬ 
ing  of  food  on  the  other  hand,  on  the  expenditure  of  energy.  Because  of  this 
change  in  the  length  of  the  experiment  it  was  necessary  to  provide  the 
chamber  with  facilities  for  feeding,  watering,  and  the  collection  of  excreta. 
These  additions  to  the  respiration  chamber  are  shown  in  Fig.  2. 

Provision  for  feeding — Feed  is  introduced  through  a  metal  chute  or  feed- 
box  of  galvanized  iron,  firmly  riveted  and  soldered  to  the  front  wall  of  the 


CHANGES  IN  APPARATUS  AND  TECPINIQUE 


27 


chamber.  It  is  provided  with  a  cover,  which  fits  into  an  oil-seal,  and  with 
a  trap-door,  hinged  on  the  front  wall  of  the  chamber.  By  means  of  this 
trap-door  the  upper  half  of  the  feed-chute  may  be  entirely  closed  off  from 
the  lower  half,  the  object  being  to  prevent  a  rapid  exchange  of  air  from  the 
respiration  chamber  when  the  cover  on  top  of  the  chute  is  momentarily 
removed  and  feed  is  inserted.  When  the  trap-door  is  open  it  hangs  sus¬ 
pended  by  the  hinges.  Two  flexible  wires  (picture-cord)  connected  with  the 
trap-door  pass  through  the  side  walls  of  the  chamber,  and  the  trap  may  be 
closed  from  the  outside,  without  removing  the  cover  of  the  feed-box,  by 
pulling  on  the  wires  until  the  door  forms  a  firm  contact  with  the  projecting 
flanges,  shown  in  Fig.  2.  The  holes  through  which  the  wires  are  passed  are 
waxed,  to  prevent  leakage  of  air.  The  bottom  of  the  feed-chute  slopes 
toward  the  feed-box  at  an  angle  of  about  45°,  so  that  the  feed  slides  down 
into  the  feed-box  within  easy  reach  of  the  animal.  The  bottom  of  the  feed- 
box  is  reenforced  on  the  outside  with  matched  wooden  sheathing,  supported 
by  four  legs.  This  gives  somewhat  more  stability  and  also  eliminates  the 
possible  pull  which  would  otherwise  be  exerted  by  this  additional  weight 
on  the  front  of  the  chamber  wall.  The  feed-box  itself  is  built  of  matched 
sheathing,  snugly  fitted  against  the  inside  wall  of  the  chamber,  so  that  the 
front  bevel  or  slope  of  the  box  is  continuous  with  the  sloping  floor  of  the 
feed-chute. 

Provision  for  water — The  device  for  watering  consists  of  a  heavy,  sheet- 
metal  tank,  9  inches  wide,  20  inches  long,  and  8  inches  deep,  with  a  rounded 
bottom.  (See  c,  Fig.  1.)  The  water  is  introduced  through  a  short  pipe 
attached  to  the  bottom  at  the  rear  of  the  tank.  This  pipe  is  connected  with 
an  opening  in  the  side-wall  of  the  chamber  by  means  of  rubber  tubing,  a 
glass  water-gage  (through  which  the  water  is  siphoned  into  the  tank)  being 
attached  to  the  outside  of  the  chamber  and  connected  with  this  opening. 
The  water-tank  itself  is  attached  at  a  convenient  height  on  the  outside  of 
the  feed-box  toward  the  room  containing  the  absorber  table,  so  that  the 
water  can  be  supplied  from  the  outside  at  any  time  without  breaking  the 
air-seal  of  the  chamber.  The  water-gage  is  connected  with  the  opening  in 
the  side  of  the  chamber  by  a  piece  of  rubber  tubing,  which  forms  a  U -curve 
below  the  level  of  the  water-tank,  so  that  the  tank  can  be  completely  drained 
and  there  will  still  be  sufficient  water  in  the  tube  to  act  as  a  seal  against 
passage  of  air. 

Swivel  stanchion — The  original,  rigid  stanchion  was  replaced  by  a  modem 
steel  swivel  stanchion  such  as  is  used  in  dairy  barns.  This  gives  the  animal 
somewhat  more  liberty  of  movement  and  makes  it  easier  for  it  to  reach  the 
water-tank,  which  is  placed  at  one  side  of  the  feed-box. 

Provision  for  collection  of  urine — Although  the  respiration  experiments 
during  the  long  fasts  of  5  to  14  days  were  only  of  2  hours’  duration,  it  was 
desirable  to  collect  all  the  urine  without  loss  during  the  entire  progress  of 
the  fast,  and  provision  was  therefore  made  for  the  collection  of  the  urine 
voided  while  the  animal  was  inside  the  chamber.  The  collection  of  urine  is 
relatively  simple  when  the  animals  are  in  the  metabolism  stalls,  but  is  more 
complicated  when  they  are  in  the  respiration  chamber,  because  of  the  neces¬ 
sity  for  preventing  any  leak  in  the  air-seal  of  the  chamber.  At  the  begin¬ 
ning  of  the  experimental  series  the  urine  voided  in  the  chamber  was  collected 


28  METABOLISM  OF  THE  FASTING  STEER 

through  a  brass  pipe  attached  to  the  side  of  the  chamber.  The  end  inside 
the  chamber  was  connected  with  the  urine-funnel  by  a  piece  of  garden-hosse. 
To  the  end  outside  a  piece  of  rubber  tubing  was  attached,  the  other  end  of 
the  rubber  tubing  being  inserted  into  a  bottle  containing  a  water-seal.  !tn 
the  experiments  beginning  early  in  the  fall  of  1922,  the  following  method 
has  been  used  in  collecting  the  urine:  A  heavy  brass  tube,  4  inches  in 
diameter  and  4  feet  long,  provided  at  one  end  with  a  flange  about  l1/^  or  2 
inches  in  width,  is  projected  down  through  a  hole  in  the  floor  of  the  chamber, 
with  the  flange  resting  on  the  inside  of  the  metal  floor  of  the  respiration 
chamber.  This  tube  is  held  firmly  in  place  in  part  by  the  flooring  (7.6  cm. 
thick) ,  through  which  it  passes,  and  in  part  by  3  lag  screws  or  bolts  2  inches 
in  length,  by  which  the  flange  of  the  tube  is  screwed  to  the  floor.  The  edges 
of  the  flange  are  soldered,  as  are  also  the  heads  of  the  screws,  to  insure 
against  leakage  of  air.  This  tube  is  just  long  enough  to  allow  for  the  raising 
and  lowering  of  the  hose  inside  of  it  connecting  with  the  urine-funnel.  Only 
a  short  piece  of  hose  is  used,  which  is  weighted  with  lead  at  the  bottom  to 
take  up  the  slack  when  the  animal  lies  down.  The  tube  leading  out  of  the 
chamber  consists  of  two  parts.  The  upper  section,  extending  downward 
from  the  floor  of  the  chamber,  is  of  ordinary  4-inch  tubing,  fitted  at  the 
bottom  with  a  small  valve  through  which  water  can  be  passed  to  the  inside 
of  the  water-seal.  The  lower  section  consists  of  a  piece  of  %-inch  brass 
pipe,  curved  to  give  a  water-seal,  and  provided  at  the  upper  end  with  a 
brass  cone  which  gradually  widens  out  to  4  inches  so  as  to  fit  against  the 
upper  part  of  the  urine-tube.  The  two  sections  are  firmly  held  together  by 
a  piece  of  automobile  inner  tubing  of  stout  rubber,  fastened  on  with  clamps. 
The  size  of  rubber  tubing  most  suitable  for  this  purpose  is  that  which  will 
require  some  stretch  when  put  around  the  metal  tubes,  so  that  the  closure 
will  be  air-tight.  The  urine,  as  collected,  flows  out  of  the  brass  tube  into  an 
appropriate  container  below.  With  this  arrangement  it  is  possible  to  collect 
the  urine  throughout  the  entire  day.  Prior  to  its  installation,  the  complete 
24-hour  collection  of  urine  could  only  be  made  if  the  animal  was  kept  stand¬ 
ing  all  the  time.  This  apparatus  for  the  collection  of  urine  while  the  steer 
is  in  the  chamber  has  functioned  satisfactorily. 

Provision  for  collection  of  feces — The  arrangement  for  collecting  feces 
consists  of  a  chute,  as  shown  in  Fig.  2.  This  chute  is  made  of  galvanized 
sheet  metal.  Its  width  dimensions  are  3  feet  by  1  foot,  and  it  extends  3  feet 
below  the  bottom  of  the  floor  of  the  chamber.  The  top  is  soldered  to  the 
inside  of  the  metal  floor  of  the  chamber.  The  bottom  is  provided  with  a 
flange  projecting  horizontally  4  inches  from  the  four  walls  of  the  chute. 
The  outside  edges  of  this  flange  have  a  2-inch  perpendicular  drop,  which  fits 
into  the  oil-seal  of  the  large  metal  container  for  collecting  the  feces.  The 
top  of  the  chute  is  covered  with  a  heavy  iron  grid,  to  prevent  the  animal 
from  stepping  down  into  the  opening.  This  grid  is  flush  with  the  floor  of 
the  chamber  (see  d,  Fig.  1),  but  is  4  inches  lower  than  the  platform  upon 
which  the  animal  rests.  During  an  experiment  the  feces  container  is  pushed 
up  tightly  against  the  feces-chute,  so  that  the  inside  wall  of  the  oil-groove 
fits  closely  against  the  horizontal  flare  of  the  chute,  thus  preventing  the 
feces  from  dropping  into  the  oil-seal.  As  shown  in  Fig.  2,  the  oil-seal  has 
been  broken  and  the  container  has  been  lowered  several  inches  to  secure 
clearance  for  removal. 


CHANGES  IN  APPARATUS  AND  TECHNIQUE 


29 


CHANGES  IN  THE  TECHNIQUE  FOR  MEASURING  THE 
RESPIRATORY  EXCHANGE 

Soda-lime 

As  a  result  of  the  development  of  the  many  forms  of  respiration  apparatus 
used  for  clinical  purposes,  chiefly  for  humans,  there  have  been  placed  upon 
the  market  several  kinds  of  soda-lime  which  are  claimed  to  be  much  superior 
to  that  regularly  used  in  the  Durham  apparatus.  Their  relative  merits  need 
not  be  discussed  here,  but  it  should  be  pointed  out  that  practically  all  of 
these  newer  types  of  soda-lime  contain  relatively  large  amounts  of  water 
and  therefore  should  not  be  used  with  this  respiration  chamber.  The  soda- 
lime  used  in  the  Durham  apparatus  contains  a  minimum  amount  of  water.0 
The  technique  for  preparing  it  has  been  described  in  earlier  publications.6 

Determination  of  Proportion  of  Air  Escaping  Through  Openings  in 

Wind-chest. 

The  wind-chest  on  the  absorber  table  has  three  air  outlets,  two  each 
10  mm.  in  diameter  and  the  third  97  mm.  The  air  discharged  through  one 
or  both  of  the  10-mm.  openings  may  be  directed  through  the  absorption 
system  and  its  carbon-dioxide  content  determined,  but  the  air  passing 
through  the  97-mm.  opening  is  discharged  into  the  laboratory  room.  With 
this  arrangement,  which  was  modeled  directly  after  the  original  aliquoting 
device  described  in  a  previous  publication,0  simultaneous  measurements  of 
the  carbon-dioxide  production  may  be  made  by  directing  the  air  from  both 
10-mm.  openings  through  duplicate  sets  of  absorbers.  But  in  the  experi¬ 
ments  with  fasting  steers  duplicate  collections  of  carbon-dioxide  were  not 
made,  and  hence  the  air  from  only  one  of  the  10-mm.  openings  was  passed 
through  the  absorption  system,  the  air  from  the  other  10-mm.  opening  being 
discharged  into  the  room.  By  reducing  the  size  of  the  97-mm.  opening  with 
different  disks  having  openings  of  different  sizes,  the  amount  of  the  aliquot 
passing  through  the  10-mm.  opening  into  the  absorption  system  may  be 
varied,  as  explained  in  detail  in  our  earlier  publication.^ 

The  disk  factor,  or  the  relative  proportion  of  air  discharged  into  the 
absorption  system,  remains  constant  even  with  relatively  large  fluctuations 
in  the  rate  of  ventilation.  Recent  experimental  work  indicates,  however, 
that  during  the  respiration  experiment  itself  it  is  better  to  maintain  always 
the  same  rate  of  ventilation  as  that  under  which  the  disk  factor  was  estab¬ 
lished,  i.  e.,  the  discharge  into  the  wind-chest  should  be  reasonably  constant. 

The  escape  of  air  from  the  wind-chest  is  obviously  dependent  on  the 
pressure  inside  the  wind-chest.  This  is  equivalent  to  but  a  few  millimeters 
of  water  pressure,  and  yet  changes  in  pressure  inside  the  wind-chest  do 
produce  disturbances  in  the  relative  discharges  through  the  various  orifices. 
When  variations  occur  in  the  disk  factor  with  the  same  disk,  it  is  because 

°  This  soda-lime  can  be  seemed  through  Mr.  W.  E.  Collins,  555  Huntington  Avenue,  Boston, 
Massachusetts,  or  through  Stanley  Jordan  &  Co.,  93  Water  Street,  New  York  City. 

k  Atwater  and  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  42,  1905,  p.  29;  also,  Benedict,  Abder- 
halden’s  Handb.  d.  biolog.  Arbeitsmethoden,  1924,  Abt.  IV,  Teil  10,  p.  449. 

c  Benedict,  Miles,  Roth,  and  Smith,  Carnegie  Inst.  Wash.  Pub.  No.  280,  1919,  p.  103. 
d  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  61. 


30 


METABOLISM  OF  THE  FASTING  STEER 


of  changes  of  air  pressure  in  the  wind-chest.  Furthermore,  in  order  to  secure 
uniformity  and  invariability  in  the  size  of  the  aliquot  from  period  to  period 
or  from  experiment  to  experiment,  the  air  discharged  into  the  sampling  can 
with  rubber-diaphragm  top  must  always  be  discharged  against  atmospheric 
pressure.  This  pressure,  which  must  remain  neutral,  is  indicated  by  an  oil 
manometer. 

The  best  method  of  establishing  the  disk  factor  is,  first,  to  set  the  appa¬ 
ratus  in  motion  as  for  an  experiment.  The  respiration  chamber  must  then 
be  ventilated  until  it  contains  only  pure,  outdoor  air.  A  known  quantity  of 
carbon  dioxide  is  then  discharged  into  the  system  through  a  small  rubber 
tube,  inserted  directly  into  the  pipe  at  some  point  between  the  wind-chest 
and  the  blower  inside  the  respiration  chamber  which  forces  air  into  the 
wind-chest.  Formerly  it  was  recommended  that  the  carbon  dioxide  be  dis¬ 
charged  into  the  intake  side  of  this  blower.  The  prime  requisite  in  this 
procedure  is  that  all  the  carbon  dioxide  should  be  discharged  into  the  wind- 
chest  without  first  permeating  the  atmosphere  of  the  chamber.  In  a  standard 
carbon-dioxide  test  the  gas  is  diffused  directly  into  the  respiration  chamber 
and  the  carbon  dioxide  in  the  residual  air  in  the  chamber  is  determined  by 
analysis.  In  the  disk-factor  test,  however,  any  carbon  dioxide  escaping 
back  into  the  chamber  would  involve  an  error.  Consequently,  the  carbon 
dioxide  should  be  introduced  at  a  point  between  the  blower  and  the  wind- 
chest,  as  the  chance  of  leakage  into  the  chamber  is  thus  practically  elimi¬ 
nated.  Indeed,  it  may  be  introduced  into  the  same  pipe  outside  of  the 
respiration  chamber,  if  desired.  Subsequent  weighing  of  the  absorption 
vessels,  with  due  allowance  for  the  carbon  dioxide  in  the  normal  outdoor 
air,  indicates  what  proportion  of  the  total  amount  of  carbon  dioxide  intro¬ 
duced  has  been  delivered  into  the  sampling-can  and  from  there  passed 
through  the  absorption  system. 


Table  6. — Proportion  of  air  ( disk  factor )  discharged  through  ab¬ 
sorption  system  according  to  the  size  of  openings  in  wind-chest 


Diameter  in  mm.  of  openings  in  wind-chest 

Disk  factor 

10,  10,  and  29 . 

p.  ct. 
10.20 

10’  10,  and  16 . 

22.84 

10‘  and  16 . 

27.00 

10,  10,  and  60 . 

3.84 

‘The  other  10-mm.  opening  was  plugged  with  a  rubber  stopper. 


With  the  introduction  and  measurement  of  carbon  dioxide  in  the  absorp¬ 
tion  system  under  the  above  conditions,  disk  factors  have  been  established 
according  to  the  different  disks  used  in  the  97-mm.  opening,  and  for  differ¬ 
ent  rates  of  ventilation.  These  disk  factors  are  tabulated  in  Table  6.  The 
disk  factor  can  of  course  be  approximately  established  by  determining  the 
relative  area  of  the  three  openings  in  the  wind-chest,  but  this  is  not  so 
accurate  a  measure  as  the  method  just  described. 


CHANGES  IN  APPARATUS  AND  TECHNIQUE 


31 


Selection  of  Disk  Opening  to  Meet  Specific  Experimental 

Requirements 


In  any  experimental  period  the  minimum  amount  of  carbon  dioxide 
absorbed  should  be  not  less  than  4  grams,  as  the  unavoidable  error  in 
weighing  the  large  absorbers  approaches  closely  to  1  per  cent  when  the 
absorbers  have  increased  in  weight  only  4  grams.  On  the  other  hand,  when 
the  air-flow  through  the  absorbers  is  high,  so  that  a  very  large  amount  of 
carbon  dioxide  is  absorbed  in  any  given  period,  the  amount  of  water-vapor 
carried  over  from  the  soda-lime  into  the  sulphuric-acid  bottle  is  also  corre¬ 
spondingly  large.  As  it  has  been  found  that  the  particular  type  of  sulphuric- 
acid  bottle  which  may  be  conveniently  used  has  an  efficient  maximum 
absorbing  capacity  of  10  grams  of  water-vapor,  this  imposes  indirectly  a 
maximum  limit  to  the  amount  of  carbon  dioxide  that  can  be  absorbed. 
Between  these  two  extremes,  therefore,  one  must  carefully  choose  the  size 
of  the  disk  opening  to  meet  the  conditions  of  the  experiment. 

The  object  in  varying  the  size  of  the  aliquot  is  mainly  to  direct  a  sufficient 
proportion  of  the  total  air  through  the  absorbers,  so  that  the  amount  of 
carbon  dioxide  absorbed,  regardless  of  the  length  of  period,  will  be  within 
the  limits  of  error  that  might  be  introduced  in  weighing  it.  Thus,  for  small 
animals,  and  also  for  animals  which  are  fasting  or  on  submaintenance 
rations  and  which  give  off  small  amounts  of  carbon  dioxide,  a  small  disk 
opening  which  gives  a  higher  disk  factor,  i.  e.,  a  larger  aliquot,  should  be 
used.  When  the  experimental  periods  are  short,  the  aliquot  should  be  a 
larger  proportion  of  the  total  amount  of  air  than  when  they  are  long.  In 
the  24-hour  experiments,  in  which  the  individual  periods  were  8  hours  long, 
use  was  made  of  a  50-mm.  disk,  which  resulted  in  an  aliquot  representing 
only  3.84  per  cent  of  the  total  discharge  of  air.  Thus  it  was  possible  not  to 
exceed  the  maximum  absorbing  capacity  of  the  soda-lime  and  sulphuric-acid 
bottles,  even  in  a  period  as  long  as  8  hours. 


Gas-analysis  Apparatus 
Importance  of  Gas  Analysis 

The  aliquoting  device  used  in  connection  with  the  respiration  chamber 
for  steers  provides  for  the  exact  determination  of  the  carbon  dioxide  removed 
by  the  ventilating  air-current,  but  it  does  not  indicate  the  change  in  the 
carbon-dioxide  residual  in  the  chamber  during  the  experimental  period.  In 
computing  from  the  carbon  dioxide  in  the  aliquot  the  total  carbon-dioxide 
production,  correction  must  be  made,  however,  for  any  change  in  the  residual 
carbon  dioxide.  In  short  half-hour  periods  this  correction  is  particularly 
essential,  if  the  total  carbon-dioxide  production  is  to  be  determined  accu¬ 
rately.  In  periods  as  long  as  24  hours  any  changes  in  the  residual  carbon 
dioxide  might  be  disregarded  without  introducing  too  great  an  error  in  the 
final  calculations,  but  this  procedure  is  not  recommended.  For  the  deter¬ 
mination  of  the  change  in  residual  carbon  dioxide  a  small  Haldane  appa¬ 
ratus  for  carbon  dioxide  only  was  originally  used. 

In  addition  to  the  measurement  of  the  residual  carbon  dioxide,  gas 
analysis  has  another  use.  In  fasting  experiments,  in  which  the  nutritive 


32 


METABOLISM  OF  THE  FASTING  STEER 


) 


state  is  so  profoundly  affected,  it  becomes  necessary  to  know  more  accurately 
the  character  of  the  food  or  of  the  body  material  burned.  To  obtain  this 
end  the  respiratory  quotient  must  be  determined,  since  it  serves  as  an 
admirable  index  of  the  nature  of  the  material  being  katabolized.  Thus,  the 
higher  the  quotient  the  larger  the  proportion  of  carbohydrates  being  burned, 
and  conversely,  the  lower  the  quotient  the  nearer  the  approximation  to  a 
pure-fat  combustion.  The  respiratory  quotient  is  therefore  of  value  in  inter¬ 
preting  the  rate  of  change  in  the  character  of  the  metabolism  during  the 
course  of  the  fasting  period  and  likewise  in  the  subsequent  feeding  period. 
Perhaps  the  most  important  use  of  the  respiratory  quotient,  however,  in 
these  experiments  was  to  provide  a  truer  indication  of  the  calorific  value  of 
carbon  dioxide,  which  should  be  employed  in  computing  heat  by  indirect 
calorimetry  from  the  carbon-dioxide  measurements.  The  calorific  value  of 
carbon  dioxide  ranges  from  6.694  to  5.047  calories  per  liter,  depending  upon 
whether  the  combustion  is  pure  fat  or  pure  carbohydrate.  If  the  respiratory 
quotient  is  actually  determined,  then  it  becomes  unnecessary  to  assume  an 
average  respiratory  quotient  or  to  employ  the  otherwise  indispensable 
carbon  dioxide  to  heat  ratios  determined  by  Armsby,  Fries,  and  Braman.0 

With  the  original  set-up  of  the  respiration  chamber  for  steers  it  was  pos¬ 
sible  to  measure  only  the  carbon-dioxide  production.  When  the  carbon- 
dioxide  production  and  the  respiratory  quotient  are  both  known,  however, 
the  computation  of  the  oxygen  consumption  of  the  animal  is  relatively 
simple,  and  from  this  latter  value  the  calculation  of  the  heat-production  is 
most  exact.  This  is  the  main  purpose  of  gas  analysis  in  connection  with 
this  respiration  chamber.  The  direct  determination  of  the  oxygen  con¬ 
sumption  of  large  animals,  such  as  steers,  is  difficult,  because  the  ventilating 
air-current  in  the  respiration  chamber  must  be  large.  Obviously,  the  closed- 
circuit  principle,  which  has  been  so  successfully  employed  with  humans, 
would  be  impracticable,  both  on  account  of  the  complexity  of  the  apparatus 
and  because  of  the  large  amount  of  oxygen  which  must  be  directly  supplied 
in  a  closed-circuit  apparatus.  Only  with  the  Zuntz  apparatus6  has  an 
attempt  thus  far  been  made  to  determine  directly  the  oxygen  consumed  by 
the  animal.  An  application  of  the  principle  simultaneously  set  forth  by 
Jaquetc  in  Basel  and  Hasselbalchd  in  Copenhagen  seemed  advisable.  To 
secure  a  gas-analysis  apparatus,  however,  that  would  function  perfectly  and 
indicate  with  great  exactness  the  relatively  small  percentage  differences  in 
the  carbon-dioxide  increment  and  in  the  oxygen  deficit  was  a  problem  of 
no  small  magnitude.  Experience  in  the  Nutrition  Laboratory  with  the 
Sonden  gas-analysis  apparatus6  left  nothing  to  be  desired,  save  that  the 
apparatus  is  not  portable  and  can  not  be  shipped  safely. 

°  Armsby,  Fries,  and  Braman,  Proc.  Nat.  Acad.  Sci.,  1920,  6,  p.  263.  These  factors  give  the 
ratio  of  carbon  dioxide  to  heat  for  cattle,  as  determined  in  their  respiration  calorimeter  under 
definite  feeding  conditions,  and  we  found  them  invaluable  in  the  interpretation  of  our  results  on 
undernutrition. 

b  Zuntz,  Landw.  Jahrb.,  1909,  38,  Ergb.-Bd.  5,  p.  473;  also  Zuntz,  VIII.  Internat.  Physiol. 
Kongress,  Wien,  Sept.  1910.  For  further  details  see  also  Zuntz,  Jahrb.  d.  deutsch.  Landw. -Gesell- 
schaft,  1912,  27,  p.  180,  and  Umschau,  No.  5,  Jan.  1911;  also  Zuntz,  Von  der  Heide,  and  Klein, 
Landw.  Versuchs-Stationen,  1913,  79-80,  p.  806;  ibid.,  Landw.  Jahrb.,  1913,  44,  pp.  776  et  seq. 

e  Jaquet,  Verhandl.  Naturf.  Gesellsch.,  Basel,  1904,  15,  p.  252. 

d  Hasselbalch,  Respirationsforspg  paa  nyfddte  B0rn,  Bibliotek  for  Laeger,  Copenhagen,  1904, 
8,  p.  219. 

e  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  166,  1912. 


CHANGES  IN  APPARATUS  AND  TECHNIQUE 


33 


Description  of  Gas-Analysis  Apparatus 

A  practical  gas-analysis  apparatus  of  portable  type  having  the  desired 
accuracy  was,  therefore,  developed  by  Dr.  T.  M.  Carpenter,  of  the  Nutrition 
Laboratory.  This  apparatus  represents  the  principle  of  the  Haldane  appa¬ 
ratus  applied  to  the  determination  both  of  the  percentage  of  oxygen  and 
of  carbon  dioxide  in  the  air  sample,  and  it  combines  the  highly  desirable 


Fiq.  3. — Diagram  of  Carpenter  apparatus  for  exact  analysis  of  atmospheric  and  chamber  air 
The  burette  A,  with  its  smaller  bulb  d,  and  the  compensator  B,  are  immersed  in  water  in  the 
container  C.  Intercommunication  between  the  burette  and  the  carbon-dioxide  absorption 
pipette  D  and  the  oxygen  absorption  pipette  E  is  secured  by  taps  H  and  J,  and  between  the 
compensating  bulb  B  and  the  pipette  D  by  the  capillary  tee  L.  The  tap  P  provides  for 
preliminary  adjustment  to  the  open  air.  F  is  a  mercury  leveling-bulb  for  the  burette  A, 
and  G  is  a  leveling-bulb  for  the  pipette  D.  SS  is  a  water  reservoir,  with  outlet  K,  to  protect 
solution  in  E  from  air  and  serve  as  a  pressure  medium.  Pinch-cocks  a,  b,  and  c  provide  for 
introduction  or  withdrawal  of  liquids. 


( 


34  METABOLISM  OF  THE  FASTING  STEER 

features  of  great  accuracy  and  of  transportability.  One  of  its  outstanding 
characteristics  is  its  facility  of  manipulation.  This  apparatus  has  already 
been  described  in  detail  by  Dr.  Carpenter.0  Its  importance  in  respiration 
experiments  of  the  type  reported  in  this  monograph  and  its  general  adoption 
in  several  laboratories  justify  the  presentation  here,  however,  of  the  dia¬ 
grammatic  sketch  of  the  apparatus.  (See  Fig.  3.)  The  details  of  the 
method  of  calibration  and  manipulation  will  be  found  in  the  two  earlier 
publications  describing  the  apparatus.0  The  accuracy  of  the  apparatus  is 
controlled  frequently  by  determinations  of  the  carbon  dioxide  and  oxygen 
in  samples  of  outdoor  air,  since  the  composition  of  outdoor  air  has  been 
established  as  constant.* * 6 

The  Physiological  Control  of  Gas-Analysis  Apparatus 

The  gas-analysis  apparatus  of  Dr.  Carpenter  has  been  extensively  con¬ 
trolled  by  analyses  under  conditions  where  ethyl  alcohol  is  being  burned  in 
a  closed  chamber  and  the  theoretical  respiratory  quotient  for  alcohol  is 
found.  But  in  respiration  experiments  of  the  character  reported  in  this 
monograph  the  metabolism  of  the  animal  itself  serves  as  an  automatic  check 
of  the  apparatus,  since  after  the  first  few  days  of  fasting  one  would  expect 
an  approximation  to  a  pure-fat  combustion,  with  a  respiratory  quotient  but 
a  little  over  0.70.  To  use  the  actual  respiratory  quotient  determined  for  an 
animal  as  a  proof  of  the  accuracy  of  the  gas-analysis  apparatus  would  not, 
of  course,  be  legitimate  under  any  conditions  save  during  fasting.  But  the 
fasting  animal  itself  furnishes  an  excellent  control  of  the  determinations  of 
the  respiratory  exchange  in  a  respiration  apparatus.  Thus,  the  Nutrition 
Laboratory  has  for  many  years  used  respiratory  quotients  determined  on 
fasting  geese  as  a  test  of  the  accuracy  of  various  forms  of  respiration 
apparatus.  Fortunately,  the  first  extensive  application  of  the  Carpenter 
gas-analysis  apparatus  occurred  in  a  series  of  fasting  experiments,  in  which 
it  could  be  assumed  that  the  katabolism  closely  approximated  a  pure-fat 
combustion.  It  will  be  observed  in  a  later  section  of  this  monograph  (see 
pp.  157  to  161)  that  the  trend  of  the  respiratory  quotient  in  all  the  fasting 
experiments  corresponded  exactly  to  that  which  one  would  theoretically 
expect  with  a  fasting  animal. 

Installation  of  the  Gas-Analysis  Apparatus  at  Durham  and  Correction  in  Cal¬ 
culation  of  Carbon-Dioxide  Production  Necessitated  by  Its  Use 

In  the  earlier  experiments  with  this  respiration  chamber  only  the  carbon- 
dioxide  content  of  the  air  inside  the  chamber  was  determined,  a  small 
Haldane  apparatus  being  used  for  the  purpose.  After  the  development  of 
the  exceedingly  accurate  Carpenter  apparatus,  the  air  leaving  the  chamber 
was  analyzed  to  determine  both  the  carbon-dioxide  increment  and  the 
oxygen  deficit  created  by  the  animal.  Indeed,  such  analyses  were  made  in 
most  of  the  experiments  reported  in  this  monograph.  An  air  sample  may  be 
taken  at  the  exact  beginning  or  end  of  a  period,  either  by  means  of  the  well- 

°  Carpenter,  Journ.  Metabolic  Research,  1923,  4,  p.  1;  see,  also,  Benedict,  Abderhaiden’e 

Handb.  d.  biolog.  Arbeitsmethoden,  1924,  Abt.  IV,  Teii  10,  p.  628. 

6  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  166,  1912. 


CHANGES  IN  APPARATUS  AND  TECHNIQUE 


35 


known  Haldane  gas-sampler  or  by  means  of  the  sampler  designed  by 
Bailey.0  When  gas  samples  are  to  be  stored  and  subsequently  analyzed, 
the  Bailey  sampler  is  the  better.  It  is  important  at  this  point  to  emphasize 
that  the  gas-samplers,  as  well  as  the  mercury  itself,  must  be  dry,  and  the 
air,  if  it  is  to  be  stored,  should  be  sampled  after  passing  through  sulphuric 
acid  and  therefore  dry,  for  when  moist  samples  are  stored  for  12  or  more 
hours  there  is  invariably  a  loss  of  carbon  dioxide.* 6  In  our  case,  however, 
analyses  were  made  continuously  and  samples  were  rarely  stored. 

The  gas-analysis  apparatus  was  set  up  in  a  room  adjoining  that  in  which 
the  absorber  table  was  placed,  an  air  sample  being  conducted  from  the 
absorber  table  to  the  gas-analysis  apparatus  by  means  of  a  ^4-inch  metal 
pipe.  Sufficient  pressure  to  insure  a  steady  flow  of  air  was  easily  secured 
by  tapping  the  pipe  conducting  the  air  from  the  positive  blower  to  the 
absorbers  at  a  point  near  the  blower,  this  being  the  point  of  highest  pressure. 
The  samples  used  for  analysis  contained  the  normal  amount  of  moisture®  in 
the  chamber  atmosphere,  as  they  were  taken  before  the  air  passed  through 
the  first  sulphuric-acid  container.  Two  pet-cocks  in  series  were  employed 
to  regulate  the  air-current  going  to  the  gas-analysis  apparatus.  One  was 
set  open  permanently,  just  wide  enough  to  allow  the  proper  amount  of  air 
to  flow  through  the  sampling-tube  to  the  gas-analysis  apparatus ;  the  other 
was  used  as  a  shut-off.  Hence  the  amount  of  air  thus  passing  through  the 
tube  was  dependent  solely  upon  the  length  of  time  the  pet-cock  was  open. 

In  using  the  apparatus,  the  shut-off  was  opened  exactly  2  minutes  before 
the  end  of  the  period,  allowing  the  air  to  flow  to  the  gas-analysis  apparatus. 
At  the  exact  end  of  the  experimental  period  this  pet-cock  was  shut  off  and 
the  time  the  valve  had  been  opened  was  noted  with  a  stop-watch.  Obviously 
the  amount  of  air  thus  diverted  from  the  aliquot  to  the  gas-analysis 
apparatus  carried  with  it  carbon  dioxide,  which  was  diverted  from  absorp¬ 
tion  in  the  soda-lime  bottles.  Since  the  air  was  analyzed,  however,  by 
volumetric  analysis,  it  was  only  necessary  to  determine  the  volume  diverted 
during  the  time  the  valve  had  been  open,  from  which  one  could  easily 
compute  the  amount  of  carbon  dioxide  lost  from  the  aliquot.  This  volume 
was  accurately  measured  for  different  rates  of  ventilation  with  a  small  gas- 
meter  placed  at  the  outlet  of  the  sampling-tube.  A  table  of  factors  was  then 
drawn  up,  showing  the  volume  of  air  flowing  through  the  sampling-pipe  for 
the  varying  lengths  of  time  that  the  pet-cocks  had  been  open.  Since  the 
rate  of  flow  through  the  sampling-pipe  changed  very  little,  whether  the 
ventilation-rate  of  the  sampling  current  was  24  or  36  cubic  feet  per  half 
hour,  the  average  of  the  different  rates  of  ventilation  between  these  limits 
was  taken  as  a  constant  in  preparing  the  table  of  factors.  The  amount 
of  carbon  dioxide  computed  from  the  volume  of  air  passing  through  the 
sampling  pipe  and  the  determined  percentage  of  carbon  dioxide  was  added 
to  the  weight  of  carbon  dioxide  collected  in  the  absorbing  vessels,  prior  to 
the  calculation  of  the  total  amount  of  carbon  dioxide  produced  during  the 
experimental  period. 

°  Bailey,  Journ.  Lab.  and  Clin.  Med.,  1921,  6,  p.  657;  ibid.,  Journ.  Biol.  Chem.,  1921,  47,  p.  281. 

6  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  166,  1912,  pp.  106  et  seq. 

e  When  samples  are  to  be  stored,  they  must  be  taken  dry,  preferably  in  a  Bailey  Bampler,  and 
taken  at  a  point  between  the  sulphuric-acid  bottles  and  the  soda-lime  bottle,  i.  e.,  usually  from  a 
pet-cock  in  the  pipe  rising  through  the  table  and  conducting  air  to  the  soda-lime  bottles. 


36 


METABOLISM  OF  THE  FASTING  STEER 


Procedure  for  Most  Accurate  Determination  of  Respiratory  Quotient 

When  it  is  desired  to  determine  the  respiratory  quotient  with  great 
accuracy,  the  carbon-dioxide  increment  and  the  oxygen  deficit  should  be 
large,  as  the  possible  error  involved  in  the  gas-analysis  is  thereby,  theo¬ 
retically  at  least,  reduced.  Hence,  in  these  experiments,  as  a  matter  of 
safeguard,  it  was  aimed  to  establish  a  high  content  of  carbon  dioxide  (circa 
1  per  cent)  in  the  air  of  the  chamber  just  before  the  beginning  and  just 
after  the  end  of  the  experiment  and  to  determine  the  respiratory  quotient 
from  these  highly  saturated  samples.  This  condition  was  obtained  by 
leaving  the  animal  in  the  chamber  approximately  one  hour  without  venti¬ 
lation.  Respiratory  quotients  were  also  determined  throughout  the  experi¬ 
ment,  but  not  with  such  a  high  carbon-dioxide  content  of  the  chamber  air. 
With  small  animals  or  animals  on  submaintenance  rations  or  fasting,  the 
carbon-dioxide  production  per  half  hour  is  very  low,  and  in  such  cases  this 
procedure  for  determining  the  respiratory  quotient  accurately  becomes  a 
necessity. 

Principles  Underlying  Control  Tests  of  Respiration  Chamber  by 
Admitting  Known  Amounts  of  Carbon  Dioxide 

The  importance  of  making  frequent  tests  of  the  operating  efficiency  of 
the  apparatus  can  not  be  over-emphasized.  The  general  principle  of  con¬ 
ducting  gas  checks  has  already  been  described.0  At  least  two  procedures 
are  possible.  In  the  first  place,  the  respiration  chamber  may  be  thoroughly 
ventilated  with  outdoor  air  and  carbon  dioxide  may  then  be  introduced 
into  the  chamber  more  rapidly  than  it  is  withdrawn.  At  the  end  of  a  half 
hour  (the  length  of  an  ordinary  period)  one  can  weigh  the  carbon  dioxide 
accumulated  in  the  soda-lime  bottles,  correct  for  the  normal  carbon-dioxide 
content  of  the  air  entering  the  soda-lime  bottles,  correct  for  any  carbon 
dioxide  diverted  in  the  air  sample  going  to  the  gas-analysis  apparatus,  and 
finally,  compute  from  the  disk  factor  the  total  amount  of  carbon  dioxide 
that  has  left  the  respiration  chamber.  The  final  value  thus  obtained  must, 
in  this  particular  case,  be  increased  by  a  large  corrective  factor  due  to  the 
accumulation  of  carbon  dioxide  inside  the  chamber.  Indeed,  when  the  air 
of  the  chamber  is  of  outdoor  composition  at  the  start,  this  correction  factor 
may  represent  three-fourths  or  more  of  the  total  amount  of  carbon  dioxide 
introduced.  Obviously,  therefore,  this  particular  type  of  gas-check  would 
test  the  accuracy  of  the  gas-analysis  apparatus  (i.  e.,  the  determinations  of 
the  residual  carbon  dioxide)  and  the  measurement  of  the  volume  of  the 
chamber  to  a  much  greater  extent  than  it  would  the  accuracy  of  the  mechan¬ 
ical  aliquoting  device  and  of  the  absorption  system.  Indeed,  a  test  of  the 
chamber  might  be  made  with  a  very  low  ventilation-rate,  so  that  the  carbon 
dioxide  would  accumulate  inside.  In  such  a  test  the  rotary  blower  dis¬ 
charging  air  from  the  chamber  would  be  maintained  at  a  speed  only  suffi¬ 
ciently  high  to  preclude  any  back  diffusion  of  air  out  of  the  loosely  sealed 
door.  Under  these  conditions  it  would  be  possible  to  carry  out  a  test  in 
which  90  per  cent  of  the  carbon  dioxide  introduced  would  accumulate  in 
the  chamber.  Such  tests  have,  as  a  matter  of  fact,  actually  been  carried 
out,  and  are  usually  successful. 


“Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  pp.  70  et  seq. 


CHANGES  IN  APPARATUS  AND  TECHNIQUE 


37 


The  second  ideal  method  is  to  have  the  rate  of  ventilation  and  the  intro¬ 
duction  of  carbon  dioxide  so  nearly  balance  that  the  residual  carbon  dioxide 
would  be  the  same  at  the  end  as  at  the  beginning  of  the  period.  Under  these 
conditions  there  would  be  no  correction  for  the  residual  carbon  dioxide,  and 
the  test  becomes  purely  a  test  of  the  mechanical  aliquoting  device  and  the 
absorption  of  carbon  dioxide.  This  second  method  is  believed  to  be  the  best. 
It  necessitates,  however,  an  accumulation  of  the  carbon  dioxide  in  the  air 
of  the  chamber  prior  to  the  true  test  to  a  point  at  which  the  relationship 
between  addition  and  removal  can  be  held  constant  during  the  subsequent 
test.  The  point  will  obviously  vary  with  the  amount  of  carbon  dioxide 
introduced  per  half  hour.  The  amount  per  half  hour  should,  theoretically 
at  least,  closely  approximate  the  amount  which  will  probably  be  produced 
by  the  animal  under  study.  Indeed,  gas-checks  are  usually  made  with  this 
chamber  under  conditions  which  closely  represent  those  produced  by  the 
animal  under  investigation. 


Table  7. — Typical  calculation  of  a  4-hour  carbon-dioxide  check  test 
(12h04m  p.  m.  to  4h05m  p.  m.,  March  26,  1924) 


Weight  of  absorbing  vessels  at  end. 
Weight  of  absorbing  vessels  at  start 


grams . 
do.  . 


5,777.85 

5,761.10 


CO2  absorbed  from  aliquot  of  outgoing  air 


do. 


16.75 


Volume  of  aliquot  of  outgoing  air . cubio  feet. . 

CO2  in  aliquot  from  outdoor  air1  (1.23  X  1.6) . grams. 

CO2  in  aliquot  from  chamber  (16.75  —  1.97) .  do. 

CO2  in  air  escaping  through  valve .  do. 

Total  CO2  in  aliquot  from  cylinder  (14.78+0.09) .  do. 

'14.87  X  100> 


.  ,  .  .  .  .  .  / 14.87  X  100\ 

CO2  in  total  outgoing  air8 1  - — — - -  1 . 

V  3.84  / 


do. 


Residual  CO2  in  chamber  at  end . . . p.  ct. . 

Residual  CO2  in  chamber  at  start .  do.  . 


123.0 

1.97 

14.78 

0.09 

14.87 

387.24 


0.331 

0.030 


Change  in  residual  CO2 


do. 


0.301 


Change  in  residual  CO2  corrected5  (0.18X0.301X1,000) . grams. 

CO2  corrected  by  residual  (387.24+54.18) .  do.  . 


54.18 

441.42 


Weight  of  steel  cylinder  at  start 
Weight  of  steel  cylinder  at  end . 


do. 

do. 


1,402.55 

961.40 


CO2  admitted  to  chamber . 

Per  cent  CO2  withdrawn  from  chamber 


/ 441.42  X100\ 
\  441 . 15  ) 


do.  . 
p.  ct.. 


441.15 

100.06 


1  Estimated  that  each  100  cubio  feet  of  outdoor  air  contains  1.6  grams  carbon  dioxide. 

!  3.84  equals  percentage  of  total  outgoing  air  actually  passing  through  absorption  system,  i.  e., 
when  the  10,  10,  and  50  mm.  openings  are  used.  (See  Table  6,  p.  30.) 

5  Estimated  that  each  0.001  per  cent  carbon  dioxide  corresponds  to  0.18  gram  carbon  dioxide, 
as  the  volume  of  air  in  the  chamber  is  about  9,000  liters. 


In  connection  with  the  24-hour  experiments  having  periods  of  8  hours’ 
duration,  a  gas-check  extending  over  4  hours  was  made.  For  this  test  the 
disk  with  the  50-mm.  opening  was  used  in  the  larger  aperture  in  the  wind- 
chest,  the  disk  factor  for  which  had  been  established  to  be  3.84  per  cent. 
The  results  of  such  a  test  are  tabulated  in  Table  7. 


ANIMALS  USED  IN  EXPERIMENTS 

Our  first  extensive  research  with  ruminants  was  made  with  14  steers  in 
groups  of  from  2  to  5  animals.0  The  uniformity  of  results  shown  between 
the  individuals  in  each  group,  both  on  maintenance  and  on  submaintenance 
feed-levels,  indicated  that  two  well-selected  animals  would  be  sufficient  for 
a  study  of  fasting,  provided  they  do  not  vary  materially  in  age,  breeding, 
and  conformation.  If  in  any  experiment,  however,  two  similar  animals  do 
not  give  approximately  the  same  result,  then  the  particular  factor  under 
investigation  should  be  studied  with  a  larger  group.  Accordingly,  most  of 
the  work  on  fasting  was  carried  out  with  two  adult  steers  (C  and  D),  each 
weighing  about  600  kg.  These  animals  were  reasonably  close  duplicates  of 
two  of  the  large,  full-grown  steers  (A  and  B)  studied  in  the  research  on 
undernutrition.  In  order  to  study  the  influence  of  size  and  age  on  fasting 
metabolism,  a  pair  of  steers  about  12  months  of  age  (E  and  F)  were  likewise 
secured.  The  animals  in  each  pair  were  essentially  physiological  duplicates. 
Thus,  to  a  certain  extent  each  experiment  was  carried  out  in  duplicate,  each 
pair  of  animals  receiving  absolutely  the  same  treatment  with  regard  to 
environmental  temperature,  feed,  and  general  handling. 

a  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923. 

38 


GENERAL  PLAN  OF  RESEARCH 

FASTING  ON  DIFFERENT  PLANES  OF  NUTRITION 

Since  the  fundamental  problem  under  investigation  was  to  determine  the 
influence  of  fasting  upon  the  physiological  behavior  of  beef  steers,  par¬ 
ticular  attention  was  centered  on  a  study  of  the  respiratory  exchange,  the 
heat-production,  and  the  composition  of  the  urine.  The  nutritive  plane  upon 
which  the  animals  were  living  before  the  fast  was  purposely  altered,  to 
determine  the  influence  that  such  differences  in  the  nutritive  level  would 
exert  on  the  well-known  drafts  upon  the  body  organism  for  maintenance 
of  life  during  subsequent  fasting.  Thus,  several  fasts  were  carried  out  with 
steers  C  and  D  in  a  well-nourished  condition,  that  is,  after  they  had  been 
gaining  flesh  for  some  time.  In  four  instances  the  feed-level  previous  to 
fasting  was  approximately  maintenance.  In  two  instances  steers  C  and  D 
were  subjected  to  fasting  after  having  been  on  pasture  for  several  months, 
when  they  were  in  a  condition  approximating  that  of  animals  in  wild  life, 
having  a  water-rich  fill  of  green  grass,  the  flesh  being  soft,  and  the  body 
more  or  less  water-logged.  They  also  fasted  after  a  fairly  prolonged  period 
upon  submaintenance  rations,  consisting  of  approximately  one-half  of  the 
usual  caloric  intake  necessary  for  maintenance.  Since  the  changes  occurring 
in  the  animal  organism  during  the  first  two  or  three  days  of  fasting  are 
most  profound,  the  effect  of  repeated  48-hour  periods  of  fasting  with  weekly 
intervals  of  refeeding  was  studied,  to  secure  added  information  on  this  point. 
Steers  E  and  F  were  likewise  studied  during  fasting  after  submaintenance 
feeding,  and  with  them  a  special  study  was  made  comparing  the  metabolism 
during  2  days  on  feed  with  that  during  2  subsequent  days  of  fasting.  In  this 
series  maintenance  and  submaintenance  feed-levels  were  contrasted,  and  the 
relative  effects  of  timothy  and  alfalfa  hay  were  also  studied.  The  experi¬ 
mental  series  did  not  include  fasting  experiments  at  the  height  of  fattening. 

SUBSIDIARY  PROBLEMS 

Undernutrition — Since  these  fasting  experiments  followed  different  nutri¬ 
tive  planes,  each  pair  of  steers  was  fed  on  submaintenance  rations  previous 
to  one  fast,  and  further  data  were  thus  secured  on  the  influence  of  under¬ 
nutrition  upon  the  metabolism  of  steers,  which  supplement  the  findings  in 
the  earlier  report  on  undernutrition.® 

Reaction  to  ingested  food  after  fasting — The  effect  of  the  ingestion  of 
food  on  metabolism  was  determined  from  various  standpoints.  In  the  first 
place,  observations  were  made  of  the  effect  of  the  first  feed  after  fasting, 
when  the  stomach  was  practically  devoid  of  any  food.  With  steers  C  and  D 
the  metabolism  was  also  measured  under  the  regular  conditions  of  feeding, 
over  periods  lasting  from  2  to  8  hours.  In  these  cases  the  animal  was  put 
into  the  respiration  chamber  immediately  after  having  consumed  a  regular 
feed.  Of  greater  importance  was  a  series  of  continuous  four-day  respiration 
experiments  with  steers  E  and  F,  in  which  the  influence  of  the  ingestion  of 

°  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923. 

39 


40 


METABOLISM  OF  THE  FASTING  STEER 


food  was  studied  during  a  period  of  2  days  of  regular  feeding  immediately 
followed  by  2  days  of  fasting. 

Environmental  temperature — Our  earlier  research0  suggested  that  the 
metabolism  of  ruminants  occasionally  decreases  with  a  falling  temperature, 
a  phenomenon  at  variance  with  all  popular  conceptions  and  previous  inves¬ 
tigation  on  this  subject.  In  the  experimental  series  beginning  in  January 
1923,  therefore,  it  was  planned  to  include  a  study  of  the  effect  of  environ¬ 
mental  temperature  on  metabolism.  Wide  ranges  in  temperature  were  pur¬ 
posely  selected,  and  the  metabolism  of  the  animals  was  measured  at  these 
different  temperatures,  both  while  they  were  fasting  and  while  they  were  on 
different  feed-levels,  including  maintenance  and  submaintenance. 

Body  position — The  importance  attached  to  the  influence  of  standing  and 
lying  upon  the  metabolism  of  ruminants  has  brought  forth  considerable  dis¬ 
cussion  on  the  subject,  resulting  in  the  recomputation  of  much  previously 
published  work.* 6  It  seemed  desirable,  therefore,  to  supplement  our  earlier, 
rather  fragmentary  findings.0  As  it  is  a  habit  of  cattle  not  to  lie  down  for  a 
very  long  period  at  a  time,  it  is  unfortunately  impossible  to  measure  the 
metabolism  during  a  long  period  of  lying  only.  The  problem  is  not  so 
difficult  when  the  steers  are  standing,  as  they  can  readily  be  forced  to  stand. 
A  few  observations  of  the  metabolism  with  the  steer  in  the  lying  and  stand¬ 
ing  positions  were  made  during  the  period  of  this  research.  These  were 
supplemented  by  others  made  during  the  winter  of  1925-26.  From  these 
later  results  it  becomes  apparent  that  the  subject  demands  a  far  more 
critical  investigation  than  was  at  first  anticipated.  Therefore  we  do  not 
feel  justified  at  the  time  of  sending  this  manuscript  to  the  printer  (summer 
of  1926)  in  discussing  this  important  problem,  since  our  data  are  as  yet  by 
no  means  complete. 

Insensible  loss — Throughout  this  research  records  were  kept  in  24-hour 
periods  of  the  body-weight,  the  amounts  of  feed  and  water  consumed,  and 
the  weights  of  feces  and  urine  excreted.  The  data  are  therefore  available 
for  computing  the  daily  insensible  loss  of  each  of  these  four  steers  during 
the  entire  experimental  season,  both  when  they  were  fasting  and  when  on 
feed.  These  data  furnish  new  material  in  the  study  of  the  physiology  of 
ruminants  which  was  not  obtained  in  our  earlier  research  on  undemutrition.d 
In  view  of  the  close  correlation  between  the  insensible  loss  and  the  metabo¬ 
lism  already  noted  with  humans, e  it  was  considered  advisable  to  determine 
whether  this  correlation  also  exists  with  ruminants  and  how  it  is  affected 
by  fasting  as  compared  with  different  feed-levels. 

°  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  pp.  219  and  301. 

6  Fries  and  Kriss,  Am.  Journ.  Physiol.,  1924,  71,  p.  60. 

*  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  215. 

d  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  85. 

‘Benedict,  Bull.  Soc.  Sci.  d’Hygiene  Alimen.,  1923,  11,  p.  357;  ibid.,  Schweiz,  med.  Wochen- 
echr.,  1923,  53,  p.  1101;  ibid.,  The  correlation  between  perspiratio  insensibilis  and  total  metabo¬ 
lism,  Collection  of  articles  dedicated  to  the  75th  birthday  of  Prof.  I.  P.  Pawlow,  published  from 
the  Institution  of  Experimental  Medicine  in  Leningrad,  1924,  p.  193;  also,  Benedict  and  Root, 
Arch.  Intern.  Med.,  1926,  38,  p.  1. 


CHRONOLOGY  OF  THE  FASTING  RESEARCH 

The  first  fasting  experiment  was  designed  as  a  general  exploratory  meas¬ 
ure,  to  discover  how  steers  would  react  when  completely  deprived  of  food, 
since  the  opinions  with  regard  to  the  probable  outcome  were  greatly  diversi¬ 
fied.  The  general  plan  of  the  research  as  a  whole  rapidly  shaped  itself  at 
the  conclusion  of  the  first  fast,  and  a  series  of  fasts  of  5  to  14  days,  as  well 
as  a  series  of  2-  and  3-day  fasts,  were  successfully  carried  to  completion 
with  steers  C  and  D.  Later  the  factor  of  age  was  introduced  with  two 
younger  steers  (E  and  F) ,  and  the  plan  of  research  was  enlarged  to  include 
continuous  4-day  respiration  experiments.  A  chronological  list  of  the  fasting 
experiments  is  given  in  Table  8,  in  which  the  length  of  the  fast  represents 
the  time  between  the  last  feed  given  before  the  fast  and  the  first  feed  given 
after  the  fast.  The  fasting  experiments  with  steers  E  and  F  between  Decem¬ 
ber  1924  and  May  1925  represent  in  each  case  a  continuous  2-day  sojourn 
in  the  respiration  chamber  without  food,  immediately  preceded  by  a  con¬ 
tinuous  2-day  respiration  experiment  during  which  the  steer  received  feed 
(maintenance  or  submaintenance  rations)  at  the  usual  hours. 


Table  8. — Chronological  list  of  fasting  experiments 


Steer  and  date 
of  last  feed 

Length  of 
fast1 

Steer  and  date 
of  last  feed 

Length  of 
fast1 

Steer  and  date 
of  last  feed 

Length  of 
fast1 

Steer  C: 

days 

hrs. 

Steer  D: 

days 

hrs. 

Steer  E: 

days 

hrs. 

Dec.  6,  1921 

7 

9 

Dec.  6,  1921 

7 

9 

Feb.  12, 1924 

5 

3 

Jan.  4,  1922 

10 

10 

Jan.  4,  1922 

10 

10 

Apr.  8,  1924 

4 

2J 

Apr.  17,  1922 

14 

71 

Apr.  17,  1922 

14 

71 

Dec.  14,  1924 

2 

9 

June  1, 1922 

6 

ll 

June  1, 1922 

5 

4 

Jan.  14,  1925 

3 

1 

Nov.  6,  1922 

10 

1 

Nov.  6,  1922 

8 

3 

Feb.  3,  1925 

3 

1 

Jan.  3,  1923 

3 

3l 

Jan.  9,  1923 

3 

4 

Mar.  1,  1925 

2 

9 

Jan.  15,  1923 

2 

,  . 

Jan.  17,  1923 

2 

3 

Mar.  18,  1925 

2 

9 

Jan.  21,  1923 

2 

4 

Jan.  25,  1923 

2 

3§ 

Apr.  15,  1925 

2 

9 

Jan.  28,  1923 

2 

4 

Feb.  1,  1923 

2 

1* 

May  5,  1925 

2 

23 

Feb.  5,  1923 

2 

31 

Feb.  8,  1923 

2 

4 

Feb.  11,  1923 

2 

4 

Feb.  14, 1923 

2 

si 

Steer  F: 

Feb.  18,  1923 

2 

3l 

Feb.  22, 1923 

2 

31 

Feb.  12, 1924 

6 

21 

Mar.  1,  1923 

2 

31 

Mar.  5,  1923 

2 

41 

Mar.  31,  1924 

4 

21 

Mar.  8,  1923 

2 

31 

Mar.  13,  1923 

2 

31 

Dec.  19,  1924 

2 

9 

Mar.  15,  1923 

2 

3| 

Mar.  20,  1923 

2 

3* 

Jan.  20,  1925 

3 

1 

Mar.  22,  1923 

2 

31 

Nov.  4,  1923 

4 

22 

Feb.  13, 1925 

3 

1 

Nov.  4,  1923 

5 

19 

Mar.  3,  1924 

9 

3 

Mar.  25,  1925 

2 

9 

Mar.  3,  1924 

10 

3i 

May  13,  1924 

4 

2 

Apr.  22,  1925 

3 

1 

Apr.  22,  1924 

4 

2 

Nov.  11,  1924 

2 

.  . 

May  12,  1925 

3 

1 

Nov.  11,  1924 

2 

1  Length  of  fast  signifies  time  between  withholding  of  feed  and  resumption  of  feeding. 


DETAILS  OF  THE  EXPERIMENTAL  CONDITIONS 

Continuous  daily  records  were  kept  throughout  the  entire  experimental 
season  each  year  of  the  body-weight,  weights  of  drinking-water  and  feed, 
and  weights  of  urine  and  feces.  From  these  data  it  has  been  possible  to 
compute  the  daily  insensible  perspiration.  In  addition,  daily  records  were 
also  made  of  the  temperature  of  the  drinking-water,  the  temperature  of  the 

41 


42 


METABOLISM  OF  THE  FASTING  STEER 


4 

metabolism  stalls  in  which  the  animals  were  kept,  the  rectal  temperature, 
and  the  heart-rate.  Various  body  measurements  were  made  periodically, 
but  only  the  chest  circumference  was  recorded  daily,  since  it  was  believed 
that  this  is  the  best  single  measurement  indicative  of  any  change  in  flesh 
or  organized  body-tissue. 

The  routine  observed  in  securing  the  body-weights  was  as  follows:  At 
exactly  2  p.  m.  each  day  the  same  steer  was  led  onto  the  scales  and  weighed. 
He  was  then  given  water  to  drink  from  a  tub,  and  again  weighed  and  put 
into  the  stall,  and  the  next  steer  was  weighed  in  like  manner.  The  tub  of 
water  was  weighed  before  and  after  each  animal  drank,  the  decrease  in 
weight  representing  the  weight  of  water  consumed  and  also  serving  as  a 
check  on  the  measurement  of  the  body-weight,  since  the  increase  in  body- 
weight  should  agree  with  the  decrease  in  weight  of  the  tub.  Beginning  with 
November  11,  1924,  the  body-weights  were  taken  at  4h  30m  p.  m.  instead  of 
at  2  p.  m.  These  weights,  in  fact  all  records  except  chest  circumference, 
heart-rate,  and  body  temperatures,  were  checked  by  a  second  observer. 

Native  hay,  comprising  at  least  75  per  cent  of  timothy  hay,  was  given  to 
all  four  steers  from  November  1921  until  March  1925,  when  alfalfa  hay 
was  fed.  The  meal  mixture  given  to  the  adult  steers,  C  and  D,  consisted  of 
a  mixture  of  equal  parts  by  weight  of  corn  meal,  linseed  meal,  and  wheat 
bran.  The  young  steers,  E  and  F,  however,  were  given  a  mixture  of  equal 
parts  by  weight  of  linseed  meal  and  wheat  bran,  without  the  corn  meal,  the 
object  being  to  promote  growth. 

During  the  periods  of  maintenance  feeding  all  four  steers  received  hay 
twice  each  day,  i.  e.,  at  4h  30m  p.  m.  and  at  8  a.  m.  The  meal  mixture  during 
the  feeding-period  from  November  26,  1921,  to  December  6,  1921,  was  given 
only  once  each  day,  at  7  a.  m.,  but  thereafter  during  maintenance  feeding 
it  was  given  twice  daily,  at  7  a.  m.  and  about  3h  30m  p.  m.  in  the  case  of  all 
four  steers.  During  the  submaintenance  period  in  the  spring  of  1923,  steers 
C  and  D  were  fed  hay  twice  each  day,  that  is,  one  bag  containing  4.5  kg. 
of  hay  was  fed  during  the  24  hours,  approximately  one-half  of  the  bag  being 
given  in  the  late  afternoon  and  the  rest  on  the  following  morning.  No  meal 
was  given  to  steers  C  and  D  at  this  time.  In  the  case  of  steers  E  and  F,  in 
the  submaintenance  period  in  1923-24,  hay  was  fed  only  once  daily,  i.  e.,  in 
the  morning,  and  meal  in  the  late  afternoon.  In  the  submaintenance  period 
in  1924-25,  however,  these  steers  received  hay  in  the  afternoon  only  and 
no  meal  at  all.  No  meal  was  fed  to  steers  C  and  D  after  June  23,  1923,  or 
to  steers  E  and  F  after  April  18,  1924. 

The  24-hour  periods  for  the  collection  of  data  for  all  4  steers  began  and 
ended  at  2  p.  m.  during  the  experimental  season  from  November  1921, 
through  May  1924,  except  for  the  fast  in  March  1924,  with  steers  C  and  D, 
when  the  day  began  and  ended  at  7  a.  m.  In  November  1924,  and  there¬ 
after  through  the  winter  and  spring  of  1925,  the  daily  periods  were  begun 
and  ended  at  4h  30m  p.  m. 

OBSERVATIONS  ON  MATURE  STEERS  C  AND  D 

Steers  C  and  D  were  purchased  and  brought  to  the  agricultural  experi¬ 
ment  station  at  Durham,  New  Hampshire,  on  October  26,  1921.  According 
to  the  statement  of  the  farmer  from  whom  they  were  purchased,  these  steers 


CHRONOLOGY  OF  THE  FASTING  RESEARCH 


43 


were  at  that  time  about  3%  years  of  age.  They  were  both  predominantly 
of  Shorthorn  breeding,  but  steer  C  showed  a  trace  of  some  other  blood  by 
his  black  muzzle.  After  their  arrival  they  were  kept  in  temporary  quarters 
until  November  26, 1921,  when  the  metabolism  stalls  were  completed  in  the 
laboratory  for  animal  nutrition.  Their  first  feed  in  the  metabolism  stalls 
was  given  at  4h  30m  p.  m.,  November  26,  1921,  and  thereafter  the  regular 
routine  of  procedure,  as  already  outlined,  was  carried  out.  A  supply  of 
hay  rations  was  weighed  out  for  a  month  in  advance,  and  samples  were 
taken  for  analysis,  but  the  meal  ration  was  weighed  out  daily.  The  feed 
refused  was  removed  and  weighed  before  the  next  24-hour  feeding-period 
began,  and  a  record  was  kept  of  the  exact  amount  uneaten. 

Fasting  experiments  were  made  with  both  steers  on  December  6  to  13, 
1921,  and  January  4  to  14,  1922.  During  the  period  between  February  2 
and  March  21,  1922,  steers  0  and  D  had  to  be  kept  in  temporary  quarters 
again,  owing  to  a  fire  in  the  laboratory  and  the  time  required  for  repairs, 
so  that  the  daily  records  could  not  be  secured. 

Details  of  the  14-Day  Fast  in  April  1922 

A  complete  picture  of  a  fast  can  be  obtained  only  from  records  which 
indicate  the  physiological  condition  of  the  animal  before  the  fast,  during 
the  fast,  and  during  recuperation.  It  seems  inadvisable  to  incur  the  expense 
which  would  be  involved  in  publishing  the  huge  amount  of  data  representing 
in  detail  all  these  various  physiological  levels.  Accordingly,  although  in  the 
discussion  of  results  the  detailed  data  secured  during  the  progress  of  each 
fast  will  be  given  in  the  various  tables,  the  complete  daily  data  for  the 
periods  prior  to  and  following  the  fast  are  given  only  for  the  14-day  fast. 
(See  Tables  9  and  10.)  The  various  recuperation  periods  following  the 
fasts  which  did  not  exceed  5  to  7  days  were  rapid  and  similar,  and  present 
nothing  unusual  which  would  warrant  the  expense  involved  in  publishing  in 
detail  the  extensive  data  secured  during  these  periods.  During  the  longer 
10-  and  14-day  fasts,  however,  the  recuperation  was  much  slower  and  the 
data  for  the  refeeding  period  following  the  14-day  fast  are  therefore  given 
in  detail. 

In  Tables  9  and  10  the  dates  when  respiration  experiments  were  made  are 
indicated  by  asterisks.  The  experiments  in  the  respiration  chamber  were 
usually  made  in  the  morning  and  in  all  cases  where  the  “standard  metabo¬ 
lism”  (see  p.  228)  was  to  be  measured  the  afternoon  feed  of  the  day  prior  to 
the  experiment  and  the  morning  feed  on  the  day  of  the  experiment  were 
withheld,  so  that  the  animal  might  be  studied  at  least  24  hours  after  eating. 
The  body-weights  and  weights  of  water  recorded  in  these  two  tables  were 
secured  at  2  p.  m.  The  measurements  of  the  chest-girth  were  taken  just 
before  the  steer  was  weighed.  The  data  for  water,  feed,  excreta,  and 
insensible  loss  represent  total  amounts  for  24-hour  periods,  beginning  at 
2  p.  m.  on  the  given  date.  The  containers  for  the  excreta,  both  feces  and 
urine,  were  removed  at  2  p.  m.,  i.  e.,  immediately  after  weighing  the  animal, 
so  that  the  weights  of  excreta  are  those  amounts  actually  voided  between 
2  p.  m.  of  one  day  and  2  p.  m.  of  the  next  day. 

The  fast  in  April  1922  was  begun  after  the  steers  had  been  on  a  constant 
ration  of  hay  and  meal  for  17  days,  i.  e.,  since  March  31,  1922.  An  exami- 


44 


METABOLISM  OF  THE  FASTING  STEER 


Table  9. — Statistics  of  experiment  of  April  17  to  May  1,  1922 ,  steer  C 


Date 

Body-weight 

Chest- 

girth 

Water 

Feed1 

Excreta 

Insen¬ 

sible 

loss 

Stall 

temp. 

Total 

Change 

Total 

Temp. 

Hay 

Meal 

Feces 

Urine 

1922 

kg. 

kg. 

cm. 

kg. 

°C. 

kg. 

kg. 

kg. 

kg. 

kg. 

°C. 

Apr.  10. . . 

602.8 

+  4.2 

201 

35.6 

12 

8.98 

3.00 

26.57 

4.35 

17.8 

22 

Apr.  11. . . 

601.6 

-  1.2 

201 

32.2 

12 

8.90 

3.00 

25.60 

4.39 

13.0 

13 

Apr.  12. . . 

602.8 

+  1-2 

201 

32.0 

12 

8.92 

3.00 

23.30 

4.22 

13.0 

13 

Apr.  13. . . 

606.2 

+  3.4 

201 

33.8 

11 

8.96 

3.00 

26.31 

4.58 

14.2 

18 

Apr.  14. . . 

606.8 

+  0.6 

202 

32.8 

13 

8.94 

3.00 

23.08 

4.03 

17.2 

21 

Apr.  15. . . 

607.2 

+  0.4 

201 

34.4 

13 

8.94 

3.00 

23.20 

4.65 

15.4 

17 

Apr.  16. . . 

610.2 

+  3.0 

198 

33.6 

15 

8.77 

3.00 

26.38 

4.54 

16.6 

20 

Apr.  17*.. 

608.2 

198 

32.0 

14 

0.00 

0.00 

20.43 

5.25 

12.6 

20 

Apr.  18*.. 

602.0 

-  6.2 

199 

12.4 

14 

0.00 

0.00 

7.08 

7.72 

6.0 

20 

Apr.  19*.. 

593.6 

-  8.4 

198 

4.6 

14 

0.00 

0.00 

4.82 

5.26 

7.2 

20 

Apr.  20*.. 

581.0 

-12.6 

196 

0.0 

13 

0.00 

0.00 

3.95 

3.16 

2.4 

15 

Apr.  21*.. 

571.4 

-  9.6 

197 

3.8 

13 

0.00 

0.00 

2.91 

2.03 

3.2 

20 

Apr.  22*.. 

567.0 

-  4.4 

196 

9.6 

17 

0.00 

0.00 

3.35 

3.84 

4.2 

22 

Apr.  23*.. 

565.2 

-  1.8 

196 

0.2 

14 

0.00 

0.00 

2.25 

2.18 

3.8 

22 

Apr.  24*. . 

557.2 

-  8.0 

196 

4.4 

20 

0.00 

0.00 

3.22 

1.92 

3.6 

22 

Apr.  25*.. 

552.8 

-  4.4 

196 

3.2 

17 

0.00 

0.00 

1.28 

2.09 

4.0 

23 

Apr.  26*.. 

548.6 

-  4.2 

194 

4.6 

18 

0.00 

0.00 

0.69 

2.12 

4.8 

20 

Apr.  27*.. 

545.6 

-  3.0 

194 

5.2 

18 

0.00 

0.00 

2.60 

4.63 

2.0 

22 

Apr,  28*.. 

541.6 

-  4.0 

193 

0.0 

19 

0.00 

0.00 

1.21 

2.01 

3.0 

21 

Apr.  29*.. 

535.4 

-  6.2 

193 

2.2 

19 

0.00 

0.00 

1.14 

1.61 

3.6 

21 

Apr.  30*.. 

531.2 

-  4.2 

193 

4.8 

17 

0.00 

0.00 

0.92 

2.35 

3.4 

21 

May  1*. . 

529.4 

-  1.8 

193 

1.8 

16 

3.79 

0.00 

0.85 

0.97 

4.0 

19 

May  2... 

529.2 

-  0.2 

193 

15.4 

16 

4.46 

0.00 

2.38 

1.71 

6.6 

22 

May  3 . . . 

538.4 

+  9.2 

193 

24.4 

17 

7.31 

0.00 

7.08 

2.47 

7.0 

19 

May  4 . . . 

553.6 

+  15.2 

193 

20.2 

15 

7.33 

0.00 

13.73 

2.49 

6.2 

14 

May  5... 

558.8 

+  5.2 

193 

21.4 

16 

7.18 

0.00 

15.48 

2.26 

7.4 

19 

May  6 . . . 

562.2 

+  3.4 

196 

20.6 

13 

8.36 

0.00 

18.56 

2.90 

8.0 

19 

May  7... 

561.8 

-  0.4 

194 

32.8 

18 

8.13 

0.00 

20.13 

2.72 

8.0 

18 

May  8 . . . 

571.8 

+  10.0 

196 

20.6 

13 

0.00 

0.00 

18.86 

3.78 

5.2 

18 

May  9*.. 

564.6 

-  7.2 

193 

0.6 

16 

8.98 

4.00 

13.11 

3.09 

10.4 

21 

May  10. . . 

551.6 

-13.0 

193 

31.0 

15 

8.31 

4.00 

16.70 

4.03 

12.6 

21 

May  11 . . . 

561.6 

+10.0 

193 

32.2 

15 

6.96 

4.00 

20.02 

3.04 

13.2 

19 

May  12... 

568.6 

+  7.0 

193 

36.0 

12 

8.42 

4.00 

22.60 

2.87 

14.6 

20 

May  13. . . 

577.0 

+  8.4 

196 

35.8 

12 

8.24 

4.00 

24.41 

3.17 

15.0 

19 

May  14. . . 

582.4 

+  5.4 

196 

35.8 

12 

8.58 

4.00 

26.06 

3.23 

17.0 

20 

May  15. . . 

584.4 

+  2.0 

196 

38.6 

13 

8.93 

4.00 

25.98 

3.82 

17.4 

20 

May  16. . . 

588.8 

+  4.4 

196 

39.2 

14 

8.84 

4.00 

26.54 

4.62 

15.2 

17 

May  17. . . 

594.4 

+  5.6 

197 

37.8 

14 

8.83 

4.00 

29.87 

4.48 

14.6 

17 

May  18. . . 

596.0 

+  1.6 

198 

39.2 

15 

8.65 

4.00 

32.43 

7.94 

15.4 

17 

May  19. . . 

592.0 

-  4.0 

197 

38.2 

13 

8.95 

4.00 

27.50 

7.13 

17.8 

20 

May  20. . . 

590.8 

-  1.2 

196 

39.2 

13 

8.70 

4.00 

32.58 

3.26 

18.8 

22 

May  21... 

588.0 

-  2.8 

196 

38.6 

13 

8.96 

4.00 

30.08 

3.54 

20.4 

24 

May  22. . . 

585.6 

-  2.4 

196 

38.8 

13 

8.92 

4.00 

27.92 

4.08 

16.4 

22 

May  23. . . 

589.0 

+  3.4 

196 

39.4 

15 

8.95 

4.00 

26.98 

4.62 

16.8 

20 

May  24. . . 

593.0 

+  4.0 

196 

40.8 

14 

8.99 

4.00 

28.18 

4.40 

16.4 

21 

May  25. . . 

597.8 

+  4.8 

197 

37.4 

13 

8.98 

4.00 

25.10 

4.47 

17.6 

22 

May  26. . . 

601.0 

+  3.2 

198 

39.2 

12 

8.87 

4.00 

28.81 

4.56 

16.6 

21 

May  27... 

603.2 

+  2.2 

199 

39.6 

14 

8.92 

4.00 

27.59 

5.18 

14.0 

16 

May  28. . . 

609.0 

+  5.8 

199 

35.0 

14 

8.99 

4.00 

29.34 

6.57 

17.2 

22 

May  29. . . 

603.8 

-  5.2 

199 

38.6 

13 

8.92 

4.00 

29.31 

5.61 

18.4 

24 

May  30. . . 

602.0 

-  1.8 

201 

38.8 

12 

7.62 

3.97 

31.96 

4.97 

16.6 

22 

May  31*.. 

598.8 

-  3.2 

199 

40.2 

15 

8.91 

4.00 

26.61 

4.71 

16.8 

23 

June  1*. . 

603.8 

+  5.0 

1  50  gm.  salt  also  eaten  on  April  12  and  16,  and  May  2,  6,  10,  19,  23.  and  29 


CHRONOLOGY  OF  THE  FASTING  RESEARCH 


45 


Table  10. — Statistics  of  experiment  of  April  17  to  May  1,  1922,  steer  D 


Date 

Body-weight 

Chest- 

girth 

Water 

Feed1 

Excreta 

Insen¬ 

sible 

loss 

Stall 

temp. 

Total 

Change 

Total 

Temp. 

Hay 

Meal 

Feces 

Urine 

1922 

kg. 

kg. 

cm. 

kg. 

eC. 

kg . 

kg. 

kg. 

kg. 

kg. 

°C. 

Apr.  10. . . 

614.6 

+  0.8 

208 

31.4 

12 

8.96 

3.00 

21.62 

4.49 

15.4 

22 

Apr.  11.-. . 

616.4 

+  1.8 

208 

29.6 

12 

8.82 

3.00 

22.29 

4.54 

11.6 

13 

Apr.  12. . . 

619.4 

+  3.0 

208 

29.4 

12 

8.84 

3.00 

24.26 

4.92 

12.8 

13 

Apr.  13... 

618.8 

-  0.6 

208 

31.8 

12 

8.86 

3.00 

22.65 

4.68 

14.2 

18 

Apr.  14 . . . 

621.0 

+  2.2 

208 

31.8 

15 

8.92 

3.00 

22.23 

4.88 

15.0 

21 

Apr.  15. . . 

622.6 

+  1.6 

208 

31.8 

15 

8.94 

3.00 

22.34 

4.75 

13.2 

17 

Apr.  16. . . 

626.0 

+  3.4 

208 

29.6 

13 

8.90 

3.00 

22.26 

5.50 

15.8 

20 

Apr.  17*.. 

624.0 

210 

32.4 

15 

0.00 

0.00 

19.06 

5.71 

12.4 

20 

Apr.  18*.. 

619.2 

-  4.8 

206 

7.8 

13 

0.00 

0.00 

7.42 

6.73 

4.2 

20 

Apr.  19*. . 

608.6 

-10.6 

206 

8.4 

14 

0.00 

0.00 

5.47 

6.98 

5.2 

20 

Apr.  20*.. 

599.4 

-  9.2 

203 

5.2 

13 

0.00 

0.00 

3.81 

3.20 

4.2 

15 

Apr.  21*. . 

593.4 

-  6.0 

203 

0.0 

0.00 

0.00 

1.42 

2.43 

3.0 

20 

Apr.  22*. . 

586.6 

-  6.8 

203 

7.8 

17 

0.00 

0.00 

2.54 

2.29 

3.8 

22 

Apr.  23*.. 

585.8 

-  0.8 

203 

0.0 

0.00 

0.00 

1.81 

1.57 

3.6 

22 

Apr.  24*.. 

578.8 

-  7.0 

203 

6.8 

19 

0.00 

0.00 

1.39 

1.87 

3.8 

22 

Apr.  25*. . 

578.6 

-  0.2 

202 

4.8 

17 

0.00 

0.00 

1.32 

1.92 

4.6 

23 

Apr.  26*.. 

575.6 

-  3.0 

202 

8.4 

18 

0.00 

0.00 

1.25 

7.65 

3.4 

20 

Apr.  27*. . 

571.8 

-  3.8 

203 

0.0 

0.00 

0.00 

1.33 

2.32 

3.2 

22 

Apr.  28*.. 

565.0 

-  6.8 

203 

6.8 

19 

0.00 

0.00 

1.39 

3.81 

2.8 

21 

Apr.  29*.. 

563.8 

-  1.2 

201 

4.4 

19 

0.00 

0.00 

1.08 

5.68 

4.2 

21 

Apr.  30*.. 

557.2 

-  6.6 

201 

0.0 

0.00 

0.00 

0.63 

1.90 

2.8 

21 

May  1*.. 

551.8 

-  5.4 

201 

0.0 

3.75 

0.00 

0.70 

1.10 

4.8 

19 

May  2 . . . 

548.8 

-  3.0 

201 

11.2 

17 

3.51 

0.00 

0.93 

1.92 

5.0 

22 

May  3 . . . 

555.6 

+  6.8 

201 

20.6 

17 

5.52 

0.00 

3.18 

3.98 

5.4 

19 

May  4... 

569.2 

+13.6 

203 

12.2 

14 

5.51 

0.00 

7.33 

4.22 

4.4 

14 

May  5... 

571.0 

+  1.8 

201 

10.6 

17 

6.34 

0.00 

10.45 

2.34 

5.8 

19 

May  6... 

569.4 

-  1.6 

203 

14.0 

16 

7.02 

0.00 

12.96 

3.25 

7.2 

19 

May  7... 

567.0 

-  2.4 

202 

24.8 

17 

8.92 

0.00 

14.19 

3.00 

6.6 

18 

May  8... 

577.0 

+  10.0 

203 

19.0 

15 

0.00 

0.00 

16.86 

2.53 

5.6 

18 

May  9*.. 

571.0 

-  6.0 

202 

6.4 

16 

8.85 

4.00 

13.33 

3.07 

9.8 

21 

May  10... 

564.0 

-  7.0 

201 

32.0 

15 

7.86 

4.00 

17.32 

4.00 

12.2 

21 

May  11.. . 

574.4 

+10.4 

203 

34.8 

14 

7.69 

4.00 

19.98 

3.28 

11.8 

19 

May  12. . . 

585.8 

+11.4 

203 

27.0 

14 

7.84 

4.00 

24.05 

3.13 

13.0 

20 

May  13. . . 

584.4 

—  1.4 

203 

35.0 

21 

7.78 

4.00 

23.09 

3.51 

13.6 

19 

May  14. . . 

591.0 

+  6.6 

203 

31.8 

15 

8.10 

4.00 

24.58 

4.43 

15.2 

20 

May  15. . . 

590.6 

-  0.4 

203 

32.8 

14 

8.86 

4.00 

23.36 

5.62 

14.4 

20 

May  16. . . 

592.8 

+  2.2 

203 

37.6 

15 

8.69 

4.00 

25.57 

4.76 

13.0 

17 

May  17. . . 

599.8 

+  7.0 

203 

32.4 

15 

8.06 

4.00 

26.37 

4.31 

11.8 

17 

May  18. . . 

601.8 

+  2.0 

203 

31.0 

14 

8.97 

4.00 

24.35 

4.48 

13.8 

17 

May  19  . . . 

603.2 

+  1-4 

203 

35.8 

15 

8.48 

4.00 

25.23 

5.83 

14.2 

20 

May  20. . . 

606.2 

+  3.0 

200 

33.2 

14 

8.71 

4.00 

26.16 

5.31 

14.0 

22 

May  21. . . 

606.6 

+  0.4 

206 

33.8 

15 

8.64 

4.00 

26.35 

4.92 

18.8 

24 

May  22. . . 

603.0 

-  3.6 

203 

37.2 

16 

7.81 

4.00 

31.10 

4.09 

14.8 

22 

May  23. . . 

602.0 

-  1.0 

206 

35.0 

15 

8.89 

4.00 

29.23 

4.70 

14.0 

20 

May  24... 

001.4 

-  0.6 

206 

37.0 

15 

8.25 

4.00 

28.09 

3.75 

14.6 

21 

May  25. . . 

604.2 

+  2.8 

206 

39.4 

15 

7.82 

4.00 

30.35 

3.47 

15.6 

22 

May  26. , . 

606.0 

+  1.8 

206 

37.0 

15 

8.76 

4.00 

28.32 

3.81 

14.2 

21 

May  27... 

609.4 

+  3.4 

208 

37.2 

13 

8.93 

4.00 

28.18 

3.91 

12.6 

10 

May  28.. . 

614.8 

+  5.4 

206 

36.2 

14 

8.72 

4.00 

29.68 

4.81 

15.4 

22 

May  29. . . 

613.8 

-  1.0 

206 

36.0 

15 

7.68 

4.00 

28.31 

5.78 

16.6 

24 

May  30. . . 

610.8 

-  3.0 

206 

38.6 

15 

8.40 

4.00 

28.01 

4.73 

14.2 

22 

May  31*. . 

614.8 

+  4.0 

206 

35.6 

13 

7.22 

4.00 

28.96 

5.52 

15.8 

23 

June  1* 

611  4 

Q  A 

1  50  gm.  salt  also  eaten  on  May  2,  6,  10,  19,  23,  and  29. 


46 


METABOLISM  OF  THE  FASTING  STEER 


nation  of  the  detailed  records  in  Tables  9  and  10  shows  that  from  the  begin¬ 
ning  of  the  fast  on  April  17  there  was  a  steady,  pronounced  loss  in  weight 
with  both  animals,  which  persisted  throughout  the  entire  fast.  The  water 
intake  also  fell  off  noticeably,  the  animals  occasionally  refusing  to  drink  at 
all.  The  decrease  in  the  daily  weight  of  feces  was  fairly  uniform.  The 
volume  of  urine  fluctuated  considerably,  although  the  general  average  shows 
a  similar  decrease.  The  insensible  loss  dropped  noticeably  after  withholding 
of  feed,  but  with  the  resumption  of  feeding  it  gradually  regained  a  high 
level.  The  stall  temperature  remained  reasonably  constant  throughout  the 
entire  period  from  April  10  to  June  1.  The  chest  circumferences  showed 
characteristic  decreases  during  the  fasting  period  and  a  slow  increase  subse¬ 
quently,  although  on  the  first  of  June,  at  the  end  of  the  refeeding  period, 
the  chest  circumference  of  neither  animal  had  returned  to  its  original 
magnitude. 

Steer  D  recuperated  much  more  slowly  on  the  ration  of  hay  only  than 
did  steer  C  after  this  14-day  fast.  During  the  first  7  days,  when  hay  alone 
was  fed,  he  ate  nearly  1  kg.  less  per  day  than  did  steer  C  and  showed  much 
less  inclination  to  eat.  During  the  23  days  following,  when  both  hay  and 
meal  were  fed,  he  ate  less  hay  daily  than  did  steer  C,  and  although  he 
cleaned  up  the  meal  every  day,  he  left  the  general  impression  that  he  was 
much  slower  in  regaining  his  normal  vigor  than  steer  C.  Certainly  he  did 
not  gain  as  much  during  the  month  of  recuperation  after  the  14-day  fast 
as  did  steer  C,  which  made  remarkable  progress  in  so  short  a  time.  It  is 
evident,  therefore,  that  the  recuperative  capacity  of  steer  D  was  somewhat 
below  that  of  steer  C. 

Both  steers  had  regained  their  original  prefasting  weight  and  vigor  by 
June  1,  and  both  were  in  excellent  condition  for  the  fourth  fast.  Judged  on 
the  basis  of  general  appearance  and  so-called  “handling,”  they  were  both 
in  a  higher  state  of  flesh  than  they  had  been  at  any  previous  time  since  they 
were  purchased.  Steer  C  had  made  an  especially  rapid  improvement  during 
the  month  of  refeeding.  He  took  on  flesh  rapidly  and  carried  a  good  cover¬ 
ing  of  flesh.  In  live  weight  he  had  almost  overtaken  steer  D,  which  had 
weighed  16  kg.  more  at  the  beginning  of  the  fast.  Steer  D  also  had  taken 
on  considerable  flesh  and  looked  in  excellent  condition,  but  his  total  increase 
in  weight  was  not  so  large  as  that  of  steer  C. 

During  the  lasti  6  days  of  this  fast,  records  were  kept  of  the  time  spent 
standing  and  lying  during  each  24-hour  period. 

General  Observations  During  the  14-Day  Fast 

The  first  feed  withheld  was  the  afternoon  feed  on  April  17.  Both  animals 
were  placed  in  the  respiration  chamber  on  this  date,  steer  C  in  the  morning 
and  steer  D  in  the  afternoon,  but  since  both  had  been  fed  about  6h  30m  a.  m., 
the  measurements  do  not  represent  standard  metabolism.  At  feeding-time 
(about  4  p.  m.)  on  April  17,  steer  D  was  very  noisy  and  restless,  but  steer  C 
was  somewhat  less  active. 

On  the  morning  of  April  18,  at  approximately  5h  30m  a.  m.,  about  50  grams 
of  the  urine  of  steer  C  were  lost.  Both  animals  were  much  quieter  on  the 
morning  of  April  18,  steer  D  lying  down  much  of  the  time.  On  April  18 
steer  C  was  in  the  respiration  chamber  from  shortly  after  9  a.  m.  until 


CHRONOLOGY  OF  THE  FASTING  RESEARCH 


47 


12b  25m  p.  m.  He  was  weighed  and  watered  as  usual  at  2  p.  m.  Steer  D  was 
studied  in  the  respiration  chamber  on  the  afternoon  of  April  18. 

During  the  afternoon  of  April  18,  steer  C  was  very  restless  in  the  stall, 
continually  lying  down  and  rising.  When  lying,  he  kicked  and  lowed 
spasmodically.  These  symptoms  (supposedly  of  colic)  started  shortly  after 
he  was  watered  at  2  p.  m.  and  continued  until  5h  45m  p.  m.,  when  he  lay 
down  and  became  quiet  for  the  rest  of  the  evening.  The  continuous  effort 
of  rising  and  lying  down,  together  with  the  apparent  colic,  seemed  to  weaken 
him  somewhat,  as  he  was  very  relaxed  during  the  rest  of  the  night. 

About  4  a.  m.  on  April  19,  steer  C  urinated  while  lying  down.  This  was 
the  first  time  in  our  experience  that  an  animal  had  urinated  while  lying,  and 
it  suggested  that  the  steer  felt  too  weak  to  rise.  Some  urine  was  unavoid¬ 
ably  lost,  as  a  consequence.  The  rectal  temperature  during  this  period  of 
colic  was  normal,  but  the  volume  of  urine  passed  was  almost  double  the 
normal  amount.  On  April  19,  both  animals  behaved  normally,  although 
steer  C  still  showed  signs  of  fatigue,  especially  after  coming  out  of  the 
respiration  chamber,  when  he  lay  down  immediately  and  remained  in  this 
position  practically  all  the  afternoon. 

Both  steers  were  remarkably  quiet  and  inactive  up  to  the  third  day  of 
fasting,  April  20,  except  for  the  first  afternoon,  April  17,  and  to  a  less  extent 
during  the  second  day,  April  18.  They  had  not  shown  any  particularly 
pronounced  anxiety  for  feed,  as  indicated  by  restlessness  or  lowing,  and 
certainly  showed  no  distress.  On  the  sixth  day  of  fasting,  April  23,  they 
were  still  doing  well,  with  no  signs  of  distress  or  other  disturbance. 

The  feces  of  both  animals  were  still  fairly  firm  on  the  fourth  day,  April  21, 
but  the  amounts  were  becoming  markedly  smaller.  On  the  seventh  day, 
April  24,  the  feces  of  steer  C  were  somewhat  softer.  During  the  evening, 
between  6  p.  m.  and  8h  30m  p.  m.,  he  passed  from  15  to  20  grams  of  material 
rather  solid  in  form,  reddish  in  appearance,  and  resembling  tissue,  slightly 
bloody,  and  mixed  with  mucus.  The  assistant  on  watch  reported  that  he 
strained  considerably  in  passing  this.  The  material  was  extremely  offensive 
in  odor.  Steer  D  behaved  as  usual. 

On  the  eighth  day,  April  25,  the  feces  of  steer  C  were  very  loose,  but 
there  was  no  change  in  rectal  temperature  and,  so  far  as  could  be  seen  from 
general  observation,  he  was  very  bright  and  acted  as  usual.  No  change  was 
noted  with  steer  D. 

On  the  ninth  day,  April  26,  steer  C  behaved  as  usual,  being  quiet  and 
alert.  The  feces  of  steer  D  were  becoming  loose  or  soft  at  this  time,  while 
those  of  steer  C  wrere  becoming  firm  and  pilular  again,  although  they  were 
not  exceedingly  dry.  Both  animals  still  rose  from  the  lying  position  with 
apparent  ease,  showing  no  signs  of  weakness  or  of  having  to  exert  particular 
effort  in  rising.  In  lying  down,  however,  they  relaxed  more  suddenly  after 
they  wrere  nearly  down  than  they  did  when  on  feed.  This  was  noticed  with 
steer  C,  especially  after  his  attack  of  colic  on  the  second  day,  from  which 
he  seemed  otherwise  to  have  entirely  recovered.  This  relaxation  on  the 
part  of  the  steers  after  they  were  nearly  down  was  probably  in  part  due  to 
the  narrowness  of  the  stalls,  which  gave  them  less  opportunity  to  spread 
their  legs. 


48 


METABOLISM  OF  THE  FASTING  STEER 


During  the  morning  of  the  tenth  day,  April  27,  steer  D  urinated  for  the 
first  time  while  lying  down,  and  approximately  100  grams  of  urine  were 
spilled. 

Both  animals  acted  somewhat  stiff  on  April  28,  and  hunched  their  backs 
somewhat  when  led  from  the  stalls  to  the  respiration  chamber.  Their  gait 
was  slightly  unsteady,  perhaps  due  to  weakness.  The  consistency  of  the 
feces  varied  with  different  defecations,  being  sometimes  very  soft.  Those 
of  steer  C  were  soft  when  voided  in  the  chamber,  a  fact  which  suggests  a 
possible  influence  of  the  exertion  of  prolonged  standing. 

There  was  no  unusual  behavior  of  the  steers  on  April  29.  On  the  evening 
of  April  29,  i.  e.,  after  12  days  of  fasting,  tests  of  the  acidity  of  the  urine 
were  begun,  on  the  supposition  that  the  steers  had  reached  a  carnivorous 
condition  and  were  living  on  their  own  body-tissue,  and  that  their  urine 
should  consequently  give  an  acid  reaction  to  litmus  paper  rather  than  the 
characteristic  alkaline  reaction  of  the  urine  of  herbivora. 

Both  steers  were  in  the  respiration  chamber  on  the  morning  of  May  1, 
the  fourteenth  day  of  the  fast,  and  at  2  p.  m.  the  fast  ended.  Steer  C  was 
weighed,  fed  1,810  grams  of  hay,  and  put  into  the  chamber  again  immedi¬ 
ately  after  eating.  The  respiration  experiment  was  continued  from  4  p.  m. 
until  approximately  10  p.  m.,  the  purpose  being  to  note  the  change  in  the 
respiratory  quotient  and  to  measure  the  rise  in  the  carbon-dioxide  production 
which  follows  the  ingestion  of  food. 

Summarized  Details  of  Other  Fasts  of  Steers  C  and  D 

Steers  C  and  D  were  subjected  to  their  fourth  fast  on  June  1-7, 1922,  and 
at  10  a.  m.  on  June  10,  1922,  they  were  turned  out  to  pasture.  Here  they 
remained  until  November  6,  1922,  when  a  fasting  experiment  after  pasture 
feeding  was  made.  They  were  brought  to  the  laboratory  at  8  a.  m.,  Novem¬ 
ber  6,  1922,  after  having  had  their  last  feed  on  pasture  that  morning,  and 
the  fasting  period  began  at  once.  Both  steers  were  in  better  condition  of 
flesh  at  the  beginning  of  this  fast  than  they  had  been  at  any  time  since  they 
were  purchased.  Steer  C  was  especially  well  fleshed;  in  fact,  he  weighed 
approximately  100  kg.  more  than  at  the  start  of  any  previous  fast.  Steer  D 
weighed  about  75  kg.  more  than  he  had  prior  to  the  previous  fasts.  This 
excess  in  weight,  however,  probably  did  not  entirely  represent  organized 
body-tissue,  but  in  part  liquid  mass  of  fill,  due  to  the  green  feed. 

Between  January  3  and  June  5,  1923,  steers  C  and  D  were  subjected  to  a 
series  of  intermittent  fasts  of  from  48  to  72  hours  in  length.  During  the 
intervals  between  these  short  fasts  until  March  28  a  constant  daily  ration 
of  9  kg.  of  hay  and  2  kg.  of  meal  was  given.  During  this  time  steer  C  was 
subjected  to  11  and  steer  D  to  10  fasts.  Between  March  28  and  April  25 
the  daily  ration  for  both  steers  consisted  of  9  kg.  of  hay  only.  After 
April  25  the  ration  was  reduced  to  4.5  kg.  of  hay  until  June  5  for  steer  C 
and  June  7  for  steer  D,  when  the  ration  was  again  increased  to  9  kg.  of  hay, 
which  level  was  maintained  until  June  22.  A  special  feature  of  these  short 
fasts  was  a  study  of  variations  in  environmental  temperature,  with  a  view 
to  determining  if  extremes  in  temperature  would  alter  the  metabolism 
materially. 


CHRONOLOGY  OF  THE  FASTING  RESEARCH 


49 


Both  steers  were  turned  out  to  pasture  at  12h  20m  p.  m.,  June  23,  1923.  On 
June  22,  before  going  to  pasture,  steer  C  weighed  666.4  kg.  and  steer  D 
weighed  637.4  kg.  The  animals  were  brought  back  to  the  barn  again  on 
October  31,  1923,  and  placed  in  a  small  pasture  adjoining  it  for  4  days. 
Between  3  and  4  p.  m.,  November  4,  1923,  they  were  placed  in  stalls  in  this 
barn,  without  feed,  preparatory  to  respiration  experiments  beginning  on  the 
morning  of  November  5.  At  8  a.  m.,  November  5,  they  were  brought  to  the 
metabolism  laboratory  and  weighed,  steer  C  weighing  at  this  time  735.6  kg. 
and  steer  D  717.2  kg.  They  were  weighed  again  at  2  p.  m.,  November  5, 
and  the  collections  of  feces  and  urine  for  the  5-day  fasting  period  were 
begun  at  this  time. 

After  their  fast  in  November  1923,  steers  C  and  D  were  again  removed 
from  the  metabolism  stalls  to  the  barn,  where  each  was  fed  regularly  9  kg. 
of  hay  per  day  until  December  21.  On  this  date  the  daily  ration  for  each 
animal  was  reduced  to  4.5  kg.  (i.  e.,  a  50  per  cent  maintenance  ration)  and 
continued  at  this  level  through  the  morning  feed  of  March  3,  1924,  when 
the  steers  were  subjected  to  a  10-day  fast.  This  reduction  in  feed  was  made 
for  the  specific  purpose  of  placing  these  animals  upon  the  same  submain¬ 
tenance  ration  as  was  given  to  steers  A  and  B  in  the  earlier  research,  with 
the  idea  of  studying  the  effect  of  a  fast  following  a  reasonably  prolonged 
period  of  undernutrition.  On  February  25,  1924,  steers  C  and  D  were 
moved  from  the  bam  to  the  metabolism  stalls,  where  the  collection  and 
aliquoting  of  feces  could  again  be  made.  This  allowed  one  complete  week 
before  the  fasting  began  in  which  they  could  become  adjusted  to  the  differ¬ 
ence  in  temperature  and  the  greater  restriction  of  the  metabolism  stalls.  The 
urine  and  feces  were,  as  usual,  collected  in  24-hour  periods.  The  daily 
periods  were  from  2  p.  m.  to  2  p.  m.  until  March  3.  March  3^  was  only 
a  17-hour  day,  when  the  feces  and  urine  were  collected  from  2  p.  m.,  March 
3,  to  7  a.  m.,  March  4.  On  March  4  and  thereafter  throughout  this  fast  the 
animals  were  weighed  and  watered  at  7  a.  m.  daily,  so  that  two  separate 
collections  of  feces  and  urine,  representing  separate  day  and  night  periods, 
could  be  made. 

The  study  of  the  respiratory  exchange  and  the  energy  transformations  in 
the  fasts  between  November  1921  and  March  1924  was  based  upon  a  series 
of  relatively  short  respiration  experiments.  Many  of  the  experiments  on 
ruminants  by  earlier  investigators  have  been  made  in  respiration  chambers 
or  calorimeters  in  which  the  experimental  periods  were  24  hours  in  length. 
Consequently,  with  steers  C  and  D  an  experiment  was  made  in  April  and 
May  1924,  respectively,  in  which  each  animal  remained  inside  the  respira¬ 
tion  chamber  for  3  days  continuously.  Unweighed  amounts  of  drinking- 
water  were  allowed,  as  desired,  a  tub  being  placed  in  the  chamber  for  this 
purpose  and  water  being  introduced  through  a  short  piece  of  rubber  tubing 
connecting  the  tub  with  the  outside  of  the  chamber.  No  attempt  was  made 
to  determine  the  amount  of  urine  and  feces  passed.  The  time  was  too  short 
to  bring  these  animals  back  to  first-class  condition  for  these  fasts.  They 
had  come  in  from  pasture  the  preceding  November,  full  of  green  grass  and 
in  excellent  condition.  They  were  then  given  a  one-half  maintenance  ration 
for  the  better  part  of  the  winter,  after  which  they  fasted  for  10  days.  At 


50 


METABOLISM  OF  THE  FASTING  STEER 


the  end  of  this  fast,  when  each  animal  had  lost  on  the  average  not  far  from 
40  kg.,  they  were  each  fed  9  kg.  of  hay  daily,  steer  C  until  April  22,  when 
he  fasted  for  4  days,  and  steer  D  until  May  13,  when  he  also  fasted  for 
4  days.  At  the  beginning  of  the  10-day  fast  in  March,  which  followed  the 
long  period  of  submaintenance  feeding,  steer  C  weighed  on  the  average 
about  635  kg.  and  steer  D  622  kg.  At  the  beginning  of  his  3-day  respiration 
experiment  on  April  23,  1924,  steer  C  weighed  669.6  kg.,  and  at  the  begin¬ 
ning  of  his  3-day  respiration  experiment  on  May  14  steer  D  weighed  664.6 
kg.,  i.  e.,  each  weighed  from  35  to  40  kg.  more  than  at  the  end  of  the  sub¬ 
maintenance  period  on  March  3.  It  is  highly  improbable  that  with  but 
9  kg.  of  hay  per  day  in  a  period  of  5  or  8  weeks  the  entire  loss  during  10 
days  of  fasting  could  have  been  made  up  by  each  animal.  It  is  more  likely 
that  this  increase  in  weight  represented  largely  increase  in  fill  or  in  the 
contents  of  the  alimentary  tract,  due  to  doubling  the  quantity  of  the  ration 
and  thus  automatically  the  water  intake. 

The  chest  circumference  of  steer  C  at  the  beginning  of  the  March  fast 
was  208  cm.,  and  it  was  the  same  on  April  22,  prior  to  the  4-day  fast.  The 
chest  circumference  of  steer  D  measured  212  cm.  before  the  March  fast  and 
210  cm.  before  the  May  fast.  This  measure  of  the  condition  of  flesh  of 
steer  C  would  indicate  complete  recuperation  back  to  the  point  of  beginning 
the  10-day  fast  in  March.  This  would  not  be  entirely  true  of  steer  D,  whose 
chest  circumference  was  actually  2  cm.  less  (indicating  less  flesh),  although 
his  weight  had  increased  40  kg.  Under  these  circumstances  it  seems  prob¬ 
able  that  steers  C  and  D  were  in  a  condition  more  nearly  approximating 
undernutrition  than  a  normal  condition. 

No  records  of  insensible  loss  were  kept  during  the  feeding  period  follow¬ 
ing  the  fast  in  March  1924,  or  during  the  fasts  in  April  and  May  1924. 

Steer  C  was  in  the  respiration  chamber  continuously  from  7h45ma.  m., 
April  23,  1924,  to  7h  45m  a.  m.,  April  26,  1924,  and  steer  D  was  in  the 
chamber  continuously  from  7h  36m  a.  m.,  May  14,  1924,  to  7h  36m  a.  m.,  May 
17,  1924,  each  animal  having  been  without  food  for  24  hours  before  entering 
the  chamber.  While  in  the  chamber  the  animals  were  allowed  to  lie  or  stand 
at  will.  Careful  records  were  obtained  with  regard  to  the  amount  of  time 
spent  standing  and  lying.  These  records  have  an  important  bearing  upon 
the  interpretation  of  the  measurements  of  the  metabolism  during  the  indi¬ 
vidual  experimental  periods,  which  were  of  8  hours’  duration  at  this  time 
instead  of  the  usual  30  minutes.  As  a  general  index  of  the  total  24-hour 
metabolism  of  animals  under  conditions  of  stall  confinement,  these  8-hour 
periods  present,  theoretically  at  least,  a  much  more  perfect  picture  than  do 
short  half-hour  periods. 

No  records  of  feed  consumed  after  these  4-day  fasts  were  kept,  and  on 
May  19,  1924,  the  steers  were  turned  out  to  pasture. 

In  connection  with  an  experiment  to  determine  the  insensible  loss  under 
extremely  varying  conditions  of  feeding,  both  steers  again  fasted  for  2  days 
each,  on  November  11  and  12,  1924.  This  was  the  last  fast  conducted  with 
these  steers.  The  steers  had  been  on  pasture  since  May  19,  1924,  and  had 
been  brought  off  pasture  on  the  morning  of  November  11,  1924. 


CHRONOLOGY  OF  THE  FASTING  RESEARCH 


51 


OBSERVATIONS  ON  IMMATURE  STEERS  E  AND  F 

In  addition  to  the  study  of  the  effect  of  fasting  upon  adult  steers  on  vari¬ 
ous  nutritive  planes,  it  seemed  advisable  to  study  the  influence  of  fasting 
upon  young,  growing  animals,  which  presumably  would  react  to  the  lack 
of  food  more  acutely  than  adult  animals.  To  make  the  experiment  still 
more  critical,  it  was  proposed  to  place  these  younger  animals  upon  a  dis¬ 
tinctly  submaintenance  ration,  so  that  they  would  begin  their  fast  in  a  con¬ 
dition  of  undernutrition.  This  preliminary  preparation,  therefore,  became 
part  of  a  subsidiary  study  of  the  effect  of  undernutrition  upon  young  steers. 

Two  young,  purebred,  Shorthorn  steer  calves,  E  and  F,  were  purchased  in 
the  fall  of  1923.  Both  were  born  on  November  28,  1922.  They  had  been 
kept  in  an  ordinary  lot,  where  they  ran  loose  with  a  dozen  other  calves.  On 
October  13,  1923,  the  day  they  were  delivered  at  the  laboratory  in  Durham, 
steer  E  weighed  288.0  kg.  and  steer  F  weighed  310.8  kg.  Previous  to  their 
arrival  they  had  been  fed  a  ration  of  hay  and  silage,  with  a  small  amount 
of  grain,  which  provided  for  ordinary  growth.  They  were  consequently  in 
a  good,  vigorous,  and  thrifty  condition  and  in  a  fair  state  of  flesh,  but 
carried  no  great  amount  of  fat. 

The  24-hour  periods  for  collection  of  data  began  and  ended  at  2  p.  m.  in 
the  case  of  these  steers,  for  all  dates  from  the  beginning  of  the  experimental 
season  in  November  1923,  through  April  1924.  The  24-hour  periods  in  the 
fall  and  winter  of  1924-25,  however,  began  and  ended  at  4h  30m  p.  m. 

When  steers  E  and  F  arrived  at  Durham,  they  were  placed  at  first  in 
temporary  quarters,  but  on  November  14,  1923,  they  were  taken  to  the 
metabolism  stalls.  From  this  date  until  December  17,  1923,  they  received 
an  approximately  maintenance  ration,  consisting  of  5  kg.  of  hay  and  0.68 
kg.  of  meal  daily.  From  December  17,  1923,  to  February  12,  1924,  they 
were  fed  a  submaintenance  ration  of  2.5  kg.  of  hay  and  0.30  kg.  of  meal,  the 
amount  of  meal  being  reduced  to  0.10  kg.  on  January  28.  On  February  12, 
1924,  they  began  a  5-day  and  6-day  fasting  experiment,  respectively,  under 
the  usual  conditions  prevailing  in  the  previous  fasts,  except  that  steers  E  and 
F  started  their  fast  on  a  submaintenance  plane  of  nutrition.  Prior  to  this 
fast  the  “standard  metabolism”  (see  p.  228)  of  both  animals  was  studied  at 
intervals  of  approximately  one  week,  both  upon  the  maintenance  and  sub- 
maintenance  levels  of  nutrition.  'Special  consideration  will  be  given  to 
these  data  subsequently.  (See  pp.  228  to  234.) 

In  addition  to  the  3-day  respiration  experiments  during  the  April  and 
May  fasts  of  steers  C  and  D,  steers  E  and  F  were  also  subjected  to  a  con¬ 
tinuous  3-day  respiration  experiment  while  fasting.  On  February  29,  1924, 
following  a  short  period  of  readjustment  after  the  February  fast,  both 
animals  were  placed  on  a  daily  ration  of  5  kg.  of  hay  and  0.91  kg.  of  meal. 
This  feed-level  was  continued  until  March  31  with  steer  F  and  until  April  8 
with  steer  E,  when  each  animal  was  subjected  to  a  4-day  fast.  Daily 
records  of  live  weights,  weights  of  urine  and  feces,  and  records  of  the 
insensible  loss  were  not  obtained  previous  to  and  during  these  fasts,  as  the 
main  object  was  a  study  of  the  respiratory  exchange. 

At  the  beginning  of  these  particular  fasts  the  body-weights  of  steers  E 
and  F  were  not  far  from  those  when  they  were  first  received  at  the  labora¬ 
tory,  although  they  were  nearly  5  months  older  and  would  normally  have 


52 


METABOLISM  OF  THE  FASTING  STEER 


gained  in  weight.  Thus,  the  body-weight  of  steer  E  was  280  kg.  on  April  9, 
1924,  as  compared  with  an  initial  weight  on  November  19, 1923,  of  266.2  kg., 
and  that  of  steer  F  was  295.2  kg.  on  April  1,  1924,  as  compared  with  an 
initial  weight  of  291  kg.  The  body-weights  in  April,  therefore,  represent  a 
thinner  state,  more  nearly  approaching  the  condition  of  undemutrition. 
The  steers  had  been  fed  more  hay  and  meal  after  the  fast  in  February  1924, 
however,  than  they  had  received  during  November  and  December  1923, 
that  is,  5  kg.  of  hay  and  0.91  kg.  of  meal  per  day  as  compared  with  the 
earlier  so-called  “maintenance”  ration  of  5  kg.  of  hay  and  0.68  kg.  of  meal. 
That  they  had  fully  made  up  all  their  losses  during  the  period  of  under- 
nutrition,  and  particularly  during  the  5-day  fast  in  February,  and  at  the 
same  time  had  made  up  for  growth  is  highly  improbable.  These  animals 
were  therefore  undoubtedly  in  a  distinctly  undernourished  state  in  April. 
Their  chest  circumferences  in  April  1924  were  essentially  the  same  as  those 
at  the  time  of  their  purchase,  but  notably  greater  than  during  the  period  of 
undemutrition.  The  estimate  of  the  nutritive  plane  of  these  animals  is 
complicated  by  the  fact  that  they  were  growing,  but  the  general  conclusion 
is  that  although  not  in  a  good  state  of  flesh,  they  were  not  so  thin  in  April 
as  in  February,  at  the  beginning  of  their  longer  fasts. 

At  the  end  of  his  fast,  on  April  12, 1924,  steer  E  weighed  260.8  kg.,  having 
lost  19.2  kg.  in  the  4  days  of  fasting.  Steer  F  weighed  271.8  kg.  at  the  end 
of  his  fast  on  April  4,  1924,  having  lost  23.4  kg.  The  chest  circumference 
of  steer  E  was  145  cm.  prior  to  fasting  and  142  cm.  for  several  days  follow¬ 
ing  the  fast,  but  by  April  18  it  was  again  145  cm.  The  chest  circumference 
of  steer  F  was  150  cm.  before  the  fast  and  147  cm.  after  the  fast,  but  was 
again  150  cm.  on  April  18. 

Between  December  1924  and  May  1925  a  series  of  continuous  4-day  res¬ 
piration  experiments  were  made  with  steers  E  and  F,  with  the  object  of 
studying  the  method  of  estimating  the  fasting  metabolism  from  the  effect  of 
quantitative  variation  of  the  same  feed.  These  respiration  experiments  con¬ 
sisted  of  2  days  when  the  animal  received  feed,  followed  by  2  days  of  fasting. 
For  at  least  2  weeks  prior  to  each  experiment  and  during  the  first  2  days  in 
the  respiration  chamber  the  feed-level  was  held  constant,  either  at  main¬ 
tenance  or  submaintenance.  The  effect  of  high  and  low  environmental  tem¬ 
peratures  and  the  relative  difference  in.  the  effect  of  timothy  and  alfalfa 
hay  were  also  studied.  During  the  two  weeks  preceding  each  4-day  respira¬ 
tion  experiment  careful  records  were  kept  daily  of  the  measurements  neces¬ 
sary  for  the  computation  of  the  insensible  loss.  Chemical  analyses  of  the 
urine  and  feces  were  not  made,  however.  While  the  steer  was  in  the  chamber 
the  feces  were  collected  only  at  the  end  of  the  4  days,  as  it  seemed  more 
important  not  to  break  the  air-seal  of  the  respiration  chamber  than  to  have 
a  daily  record  of  the  weights  of  feces.  It  was  possible  in  most  instances, 
however,  to  secure  the  daily  weights  of  urine  voided,  and  samples  were  taken 
for  nitrogen  determinations. 

RECORDS  OF  LAST  INDIVIDUAL  FEED  PRIOR  TO  EACH  FAST 

The  amount  of  the  last  individual  feed  and  the  hour  at  which  it  was  given 
prior  to  each  fast  are  recorded  in  Table  11.  The  first  feed  given  to  the 
steers  following  the  fasts  was  not  the  same  in  every  case.  Since  the  interest 


CHRONOLOGY  OF  THE  FASTING  RESEARCH 


53 


lies,  however,  only  in  those  cases  where  a  respiration  experiment  was  made 
immediately  after  the  first  refeed,  the  details  regarding  the  first  feed  after 
each  fast  are  not  tabulated  here,  but  will  be  discussed  subsequently  in  con¬ 
nection  with  the  respiration  experiments.  (See  pp.  222  and  223.) 

Table  11. — Amounts  and  times  of  last  feeds  prior  to  fasts 


Steer 

Date 

Hay1 

Meal 

Time 

C  and  D  . . . 

Dec.  6,  1921 . 

kg. 
ca.  4.5 

kg. 

1.36 

6  a.  m. 

C  and  D  . . . 

Jan.  4,  1922 . 

ca.  4.0 

3.00 

6  a.  m. 

C . 

Apr.  17,  1922 . 

2.5 

1.50 

6h30m  a.  m. 

D . 

Apr.  17j  1922 . 

4.4 

1.50 

6  30  a.  m. 

C . 

June  1,  1922 . 

4.5 

2.00 

10  30  a.  m. 

D . 

June  1,  1922 . 

2.7 

2.00 

7  45  a.  m. 

C  and  D  . . . 

Nov.  6,  1922 . 

Off  p 

asture 

8  a.  m. 

C  and  D  . . . 

Jan.  3  to  Mar.  20,  1923 . 

4.5 

1.00 

8  a.  m. 

C . 

Mar.  22,  1923 . 

3.5 

1.00 

8  a.  m. 

C  and  D  .  .  . 

Nov.  4,  1923 . 

Off  p 

asture 

3  to  4  p.  m. 

C,  D,  E,  F  . 

Feb.  12  to  Apr.  8,  1924 . 

ca.  2.5 

0.00 

7  to  8  a.  m. 

C . 

Apr.  22,  1924 . 

4.5 

0.00 

8  a.  m. 

D . 

May  13,  1924 . 

4.5 

0.00 

8  a.  m. 

C  and  D  . . . 

Nov.  11,  1924 . 

Off  p 

asture 

4h30m  p.  m. 

E  and  F  . . . 

Dec.  14  and  19,  1924 . 

3.5 

0.00 

8  40  a.  m. 

E  and  F  . . . 

Jan.  14  to  Feb.  13,  1925 . 

3.5 

0.00 

5  p.  m. 

E  and  F  . . . 

Mar.  1  to  Apr.  22,  1925 . 

3.5 

0.00 

ca.  8b45m  a.  m. 

E  and  F  .  . . 

May  5  and  12,  1925 . 

3.5 

0.00 

5  p.  m. 

1  Timothy  hay  was  fed  to  steers  C  and  D  on  all  dates  and  to  steers  E  and  F  until  March  1925. 
On  Mar.  6,  1925,  at  4h30m  p.  m.  and  thereafter  steer  E  was  fed  alfalfa  hay;  on  Mar.  9,  1925,  at 
4h30m  p.  m.  and  thereafter  steer  F  was  also  fed  alfalfa  hay. 


DISCUSSION  OF  RESULTS 

BODY-WEIGHT 

No  one  factor  is  of  greater  concern  in  practical  and  experimental  nutrition 
than  is  a  true  measure  of  the  loss  or  gain  of  organized  body -tissue  resulting 
from  any  particular  level  of  feeding.  Since  there  is  seemingly  no  better 
measure  of  these  changes  than  live  body-weight,  it  has  been  almost  uni¬ 
versally  adopted  for  this  purpose.  On  a  priori  grounds,  one  can  reasonably 
assume  that  in  fasting,  with  no  food  intake,  there  must  be  a  continuous 
draft  upon  the  body-tissue.  The  magnitude  of  this  draft,  however,  is  not 
strictly  indicated  by  any  changes  which  take  place  in  live  body-weight,  for 
even  while  this  draft  may  be  going  on,  the  live  weight  may  actually  increase. 
In  most  fasting  experiments,  drinking-water  is  permitted,  which  of  course 
helps  to  increase  the  live  weight  temporarily.  On  the  other  hand,  there  are 
factors,  such  as  the  excretion  of  urine  and  feces,  which  decrease  the  live 
body-weight,  but  which  do  not  quantitatively  represent  loss  of  tissue.  It  is 
therefore  extremely  complicated  to  determine  the  true  loss  of  body-tissue 
which  takes  place  as  a  result  of  the  fasting  per  se.  Without  a  careful 
analysis  of  the  relative  influence  of  these  various  factors,  any  changes  in 
body-weight  can  present  only  a  most  inadequate  picture  of  true  losses  of 
body-tissue.  The  daily  fluctuations  in  live  weight  due  to  these  extraneous 
factors  may  be  exceedingly  large;  in  fact,  they  may  be  many  times  greater 
than  any  possible  daily  changes  (particularly  increases)  which  could  take 
place  in  the  form  of  body-tissue. 

The  gross  fluctuations  in  the  live  weights  of  cattle  from  day  to  day,  even 
with  constant  intake  of  food  and  water,  have  already  been  discussed  in 
great  detail.®  These  changes  in  live  weight,  which  are  at  times  very  large, 
can  be  definitely  traced  in  the  majority  of  instances  to  variations  in  the 
fill  or  ballast  of  ruminants  and  particularly  to  variations  in  the  water- 
content  of  the  alimentary  tract  and  of  the  bladder.  From  the  experimental 
standpoint,  it  would  be  preferable  if  the  caecum  and  the  bladder  could  be 
emptied  just  prior  to  weighing  at  the  end  of  any  given  experimental  period, 
but  obviously  this  is  impossible  in  the  case  of  ruminants.  Yet  if  both  of 
these  organs  are  emptied  just  after  the  weighing  at  the  end  of  the  24-hour 
period,  these  voidings  may  by  chance  be  credited  to  either  one  or  the  other 
of  two  different  days  and  the  live  weight  will  vary  accordingly.  The 
irregularity  in  the  quantity  and  in  the  time  of  expulsion  of  both  feces  and 
urine  is  therefore  an  important  factor  in  these  fluctuations  in  live  weight. 

The  results  obtained  during  the  undernutrition  periods  in  this  present 
research  bear  out  the  earlier  results  with  ruminants  published  from  the 
Nutrition  Laboratory,  which  showed  that  during  undernutrition  there  are 
pronounced  variations  in  the  amount  of  the  intestinal  ballast,  and  particu¬ 
larly  that  when  there  is  a  transition  from  a  low  to  a  higher  nutritive  plane, 
or  vice  versa,  the  change  is  relatively  enormous.  The  variations  which  take 
place  in  the  elimination  of  feces  under  conditions  of  fasting  were  therefore 
studied  with  special  care  in  these  fasts,  the  amount  of  each  defecation  and 

“Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  pp.  80  et  seq. 

54 


BODY-WEIGHT 


55 


of  each  urination  being  recorded,  as  well  as  the  hour  when  they  were  voided. 
Such  records  give  no  direct  measure  of  the  actual  mass  of  undigested  mate¬ 
rial  in  the  intestinal  tract  at  any  time,  but  are  essential  to  an  intelligent 
study  of  those  changes  in  body-weight  which  represent  organized  body -tissue 
apart  from  those  due  to  changes  in  fill. 

The  body-weights  of  our  steers  were  determined  on  scales  sensitive  to 
approximately  0.2  kg.  Since  the  primary  essential  in  weighing  a  nervous 
animal  is  quiet  control,  particular  care  was  taken  to  have  the  animal 
standing  still  while  the  sliding  weight  on  the  scale-beam  was  being  adjusted 
to  a  balance.  The  desirability  of  always  having  the  animals  weighed  by 
the  same  person  at  the  same  hour  of  the  day  and  as  nearly  as  possible  under 
the  same  conditions  can  hardly  be  over  estimated.  In  fact,  the  person  who 
held  the  animal  also  stood  on  the  scale  and  was  weighed  with  the  steer,  the 
scale  having  been  previously  balanced  with  the  attendant’s  weight  recorded 
on  the  upper  arm  of  the  scale  beam.  Thus  any  pull  on  the  halter  would  not 
disturb  a  correct  balance.  The  body-weights  were  therefore  recorded  with 
extreme  care,  every  precaution  being  taken  to  secure  the  highest  degree  of 
accuracy  in  the  measurements  and  in  the  time  records,  in  order  to  make  the 
weights  of  special  value  in  the  computations  of  the  gains  or  losses  per  24 
hours  and  particularly  in  the  calculation  of  the  insensible  loss. 

Lengths  of  Fasts  and  Nature  of  Feed-levels  Preceding  Them 

Of  the  4  animals  used  in  this  investigation,  steers  C  and  D  were  each  sub¬ 
jected  to  7  fasts  of  from  5  to  14  days,  one  fast  of  4  days,  one  of  3  days,  and 
11  and  10  fasts,  respectively,  of  2  days  each.  Steers  E  and  F  were  each 
subjected  to  one  fast  of  5  and  6  days,  respectively,  to  one  fast  of  4  days, 
and  to  7  and  6  fasts,  respectively,  which  were  between  2  and  3  days  in 
length.  These  fasts  followed  different  levels  of  nutrition.  All  the  fasts  of 
steers  C  and  D  from  December  1921  to  June  1922  came  after  a  preliminary 
feeding  on  hay  and  meal,  the  feed-level  ranging  from  approximate  main¬ 
tenance  to  moderate  supermaintenance.  The  fasts  of  November  1922  and 
November  1923  with  the  same  steers  took  place  after  they  had  been  on 
pasture  for  4  or  more  months,  and  the  fasts  in  March  1924  followed  2 
months  of  submaintenance  feeding.  The  short  fasts  of  steers  C  and  D, 
ranging  from  2  to  4  days,  followed  feed-levels  representing  approximate 
maintenance.  The  long  fasts  of  steers  E  and  F  in  February  1924,  like  those 
of  steers  C  and  D  in  March  1924,  followed  submaintenance  feeding,  and 
their  4-day  fasts  in  April  1924  followed  maintenance  feeding.  The  short 
2-day  and  3-day  fasts  of  steers  E  and  F  in  1925,  however,  were  not  planned 
for  a  study  of  body-weight  changes. 

The  steers  were  kept  in  metabolism  stalls  during  all  fasts  and,  with  few 
exceptions,  also  during  the  preliminary  feeding-periods  before  the  fasts,  so 
that  it  was  possible  to  secure  daily  records  of  the  live  weight,  the  weights 
of  water  consumed,  and  the  weights  of  urine  and  feces  voided.  The  result¬ 
ing  mass  of  data  has  been  given  in  detail  for  the  fasts  of  steers  C  and  D  in 
April  1922  (see  Tables  9  and  10,  pp.  44  and  45),  but  the  data  for  the  other 
fasts  will  be  found  in  the  tables  in  this  chapter  and  in  the  subsequent 
chapters  of  this  monograph. 


56 


METABOLISM  OF  THE  FASTING  STEER 


Daily  Variations  in  Body-weight  During  Fasting 

The  daily  variations  in  body-weight  have  been  tabulated  for  each  fast 
and  for  the  3  food  days  directly  preceding.  For  the  fasts  of  5  or  more  days, 
which  followed  different  feed-levels,  the  data  are  given  in  Table  12,  and  for 
the  fasts  of  2  and  3  days,  following  maintenance  feeding,  the  data  are  given 
in  Table  13.  Reference  should  also  be  made  to  Tables  17  to  20  and  Table 
27,  pages  72,  76,  78,  83,  and  100,  in  connection  with  the  following  discussion. 

Influence  of  Long  Fasts  at  Different  Levels  of  Nutrition 

Considering,  first,  the  fasts  of  5  to  14  days,  we  see  from  Table  12  that  on 
the  three  food  days  preceding  each  fast  fluctuations  in  live  weight  from  day 
to  day  appear  in  all  instances,  as  would  be  expected,  but  since  they  include 
both  gains  and  losses  which  are  practically  compensating,  the  tendency  to 
variation  around  a  uniform  live  weight  is  apparent.  During  fasting,  the 
general  picture  of  daily  variations  in  live  weight  shows  a  clear-cut  contrast 
to  the  conditions  previous  to  fasting.  The  changes  in  live  weight  are 
equally  large  for  the  first  three  or  four  days,  but  with  few  exceptions  they 
represent  only  losses.  After  the  fourth  day  the  losses  continue,  but  they 
tend  to  become  materially  less,  although  they  still  remain  somewhat 
irregular. 

A  close  examination  of  the  losses  during  different  fasts  shows  the  impor¬ 
tant  influence  which  the  prefasting  feed-level  exerts  on  losses  in  weight  for 
the  first  few  days.  The  first  four  long  fasts  of  steers  C  and  D  (see  Table  12) 
followed  relatively  similar  feed-levels,  consisting  of  hay  and  meal  and 
ranging  in  quantity  from  maintenance  to  slightly  supermaintenance.  Dur¬ 
ing  all  four  of  these  fasts  the  losses  in  live  weight  on  the  first  day  are 
similar,  but  relatively  small.  The  apparently  wide  discrepancy  between 
the  first  fast  and  the  three  following  is  directly  accounted  for  by  differences 
in  water  intake  at  the  beginning  of  the  first  24-hour  period.  In  other  wrords, 
in  the  first  fast  both  steers  drank  approximately  18  kg.  of  water  at  the 
beginning  of  the  first  24-hour  period  without  food,  and  before  each  of  the 
other  three  fasts  they  took  approximately  double  that  amount,  although 
there  was  no  material  difference  in  the  total  weight  of  urine  and  feces 
voided  on  these  days.  Excretion  of  this  water  in  the  urine  and  feces  during 
the  same  24-hour  period,  therefore,  furnishes  the  remaining  necessary  evi¬ 
dence  for  the  cause  of  these  fluctuations  in  live  weight. 

In  the  fifth  and  sixth  fasts,  which  followed  pasture  feeding  (an  entirely 
different  feed-level),  the  relative  losses  during  the  first  24-hour  period  are 
at  least  five  times  as  large  as  those  during  the  first  day  of  fasting  after  dry 
feed.  In  the  sixth  fast  (i.  e.,  in  November  1923)  the  losses  were  obtained 
only  for  the  last  5%  hours  of  the  first  24-hour  period,  but  even  for  this 
length  of  time  the  decrease  in  weight  is  approximately  11  kg.,  suggesting 
that  the  loss  for  the  total  24  hours  must  have  been  immense,  as  was  the  case 
in  the  fifth  fast  in  November  1922. 

In  the  seventh  fast  with  steers  C  and  D,  which  followed  a  submaintenance 
feed-level  of  2  months,  there  was  practically  no  loss  in  weight  during  the 
first  17  hours.  This  fact  suggests  that  when  the  fast  began  the  intestinal 
fill  must  have  been  considerably  below  the  amount  normally  present  during 


12.— Daily  changes  in  body-weight  before  and  during  fasts  of  5  to  1 4  days 


BODY-WEIGHT 


57 


at  the  end  of  the  first  fasting  day. 


58 


METABOLISM  OF  THE  FASTING  STEER 


maintenance  feeding.  The  losses  noted  during  the  submaintenance  fasts  of 
steers  E  and  F,  although  not  quantitatively  comparable  with  the  losses  of 
steers  C  and  D,  because  of  inequality  in  the  size  and  age  of  the  animals, 
are  surprisingly  high  on  the  first  day,  but  the  losses  on  the  following  days 
are  small,  characteristic  of  submaintenance  feeding. 

The  influence  of  water  intake  on  the  irregularity  of  the  loss  in  live  weight 
becomes  strikingly  manifest  between  the  first  and  the  second  day  of  fasting. 
In  the  fasts  of  5  to  14  days,  almost  without  exception  the  animals  would 
refuse  water  at  the  beginning  of  the  second  day,  after  having  fasted  for  24 
hours.  Hence,  in  most  instances,  there  was  no  intake  whatsoever  to  offset 
the  outgo,  and  the  losses  are  relatively  large.  As  further  proof  of  this  point, 
those  instances  when  the  animal  actually  did  drink  any  material  quantity 
of  water  show  the  exception  to  a  large  decrease  in  weight.  Striking  exam¬ 
ples  are  the  third  fast  of  steer  C  and  the  fifth  fast  of  steer  D.  On  the  other 
hand,  in  the  short  2-day  fasts,  which  will  be  discussed  in  detail  later  (see 
Table  13,  p.  60),  when  these  steers  refused  to  drink  at  the  beginning  of  the 
first  day,  but  drank  at  the  beginning  of  the  second  day,  the  magnitude  of 
live-weight  losses  was  reversed.  In  other  words,  it  is  purely  a  differential 
balance  produced  by  water  intake  on  the  first  and  second  days,  which  indi¬ 
cates  a  larger  loss  in  weight  on  the  second  day  than  on  the  first,  or  vice 
versa.  The  relationships  between  loss  in  weight  and  water  intake  are  of 
course  not  absolutely  proportional,  as  they  are  modified  somewhat  by  varia¬ 
tions  in  the  amount  of  urine  and  feces  voided.  The  variations  in  urine  and 
feces,  however,  are  not  by  themselves  of  sufficient  magnitude  to  account  for 
a  material  difference  in  loss  of  weight. 

The  conditions  pertaining  to  the  fasts  off  pasture  are  not  strictly  com¬ 
parable  with  the  conditions  of  the  fasts  following  dry  feed  just  mentioned, 
for  the  reason  that  animals  apparently  lose  the  semi-liquid  fill  of  grass  at 
a  much  more  rapid  rate  than  they  do  a  fill  from  hay  and  meal.  The  tre¬ 
mendous  losses  during  the  first  day  of  these  fasts  off  pasture  have  already 
been  pointed  out.  During  the  second  day  of  fasting  off  grass  the  loss  still 
tends  to  continue  at  nearly  the  same  rate  when  the  animal  does  not  drink 
water,  and  in  the  only  case  where  the  loss  is  very  low  (4.4  kg.)  the  cause 
can  immediately  be  laid  to  the  fact  that  this  is  the  only  instance  where  the 
animal  drank  water  at  the  beginning  of  that  day.  In  the  case  of  the  fast 
off  pasture  where  the  loss  is  exceptionally  large  even  on  the  second  day 
(37.4  kg.  with  steer  D),  the  cause  is  immediately  traceable  to  an  excep¬ 
tionally  large  amount  of  urine  and  feces  coincident  with  no  water  intake 
at  the  beginning  of  the  24-hour  period. 

On  the  third  day  the  effect  of  the  previous  feed-level  becomes  less  mani¬ 
fest,  and  the  weight  loss  of  both  steers  appears  to  approach  a  relatively  more 
stable  condition.  Even  the  maximum  loss  of  18.2  kg.  with  steer  C  on  the 
third  day  of  the  fast  in  November  1923  is  only  slightly  over  half  as  large 
as  the  probable  loss  on  the  second  day  of  the  same  fast.  The  loss  shows  a 
still  further  decline  on  the  fourth  day,  and  it  is  at  this  point  that  steers  C 
and  D  show  the  greatest  individual  difference.  For  the  first  four  days  the 
live-weight  losses  of  steer  C  were  in  general  greater  than  those  of  steer  D, 
and  on  the  fourth  day  his  average  loss  for  the  7  fasts  was  more  than  twice 


BODY-WEIGHT 


59 


that  of  steer  D.  On  the  other  hand,  steer  D  had  consistently  taken  much 
larger  amounts  of  water  and  a  particularly  large  amount  on  the  fourth  day. 
After  the  fourth  day  the  rate  of  the  daily  loss  of  both  animals  appears  to 
become  similar,  regardless  of  the  prefasting  feed-level  or  of  the  individual 
animal. 

The  average  daily  loss  of  steers  C  and  D  from  the  fifth  day  on  to  the 
fourteenth  is,  respectively,  3.9  and  3.7  kg.  The  close  agreement  between 
these  average  losses  after  the  fifth  day  and  the  insensible  perspiration  dur¬ 
ing  the  same  period  (see  Table  17,  p.  72)  suggests  that  after  the  fifth  day 
the  loss  in  weight  is  more  closely  representative  of  the  loss  in  body-tissue, 
i.  e.,  muscle  and  fat.  If  the  outgo  of  visible  excreta  were  always  propor¬ 
tional  to  the  intake  of  food  and  water  during  the  same  24-hour  period,  then 
any  loss  or  gain  in  weight  during  this  time  could  be  accepted  as  a  reasonably 
close  measure  of  loss  or  gain  in  body-tissue.  Under  conditions,  however, 
where  the  intake  (water  only)  from  one  day  to  another  may  vary  between 
0  and  50  kg.  and  the  visible  outgo  may  remain  fairly  uniform,  the  differ¬ 
ential  between  these  two  extraneous  factors  entirely  conceals  any  change  in 
the  body-tissue.  In  other  words,  the  live  weights  on  any  given  day  are  not 
specifically  indicative  of  a  change  in  body-tissue  unless  due  allowance  is 
made  for  the  balance  between  the  intake  and  outgo  of  visible  matter. 

In  the  earlier  literature  there  are  no  data  with  which  our  results  may  be 
compared,  except  the  experiments  of  Grouven.a  One  of  his  oxen,  which 
weighed  522  kg.,  fasted  for  8  days.  The  loss  in  weight  from  day  to  day  was, 
as  with  our  animals,  rather  large.  Considerable  irregularity  was  noted  in 
the  loss  in  weight  at  the  end  of  the  fast,  an  irregularity  which  was,  how¬ 
ever,  in  most  instances  easily  accounted  for  by  differences  in  water  intake 
or  in  the  excretion  of  urine  and  feces.  With  another  ox,  weighing  at  the 
start  420  kg.,  the  losses  in  weight  were  more  regular  than  with  the  larger 
animal.  Considerable  differences  were  noted  in  the  amount  of  water  con¬ 
sumed  by  the  smaller  ox,  and  yet  he  drank  water  every  day,  whereas  the 
larger  ox  refused  water  on  three  days.  The  volume  of  urine  with  the 
smaller  ox  remained  singularly  constant  throughout  the  entire  fast.  The 
amount  of  feces  was  large  on  the  first  day,  but  there  was  a  rapid  drop  on 
the  second  day.  Since,  as  pointed  out  by  Grouven  in  his  discussion  of  the 
nature  of  the  intestinal  ballast,  the  previous  rationing  plays  such  a  role  in 
the  changes  in  live  weight  during  fasting,  it  is  difficult  to  draw  any  strict 
comparison  between  the  data  secured  with  our  animals  and  with  those  of 
Grouven. 

Recently,  Forbes,  Fries  and  Kriss6  have  published  the  body-weights  of 
some  fasting  cows,  which  indicate  that  there  was  in  general  a  loss  in  body- 
weight  as  the  fast  progressed,  with  occasional  gains,  due  in  large  part  to 
the  amount  of  water  consumed.  The  maximum  loss  was  28.9  kg.  with  cow 
887  III,  which  fasted  for  9  days.  Cow  874  III,  which  weighed  100  kg.  more, 
lost  25.5  kg.  in  9  days. 

°  Grouven,  Physiologisch-chemische  Fiitteningsversuche.  Zweiter  Bericht  ilber  die  Arbeiten 
der  agrikulturchemischen  Versuchsstation  zu  Salzmunde,  Berlin,  1864,  pp.  147  et  seq.  (See,  also, 
p.  15  of  this  monograph.) 

*Forbes,  Fries,  and  Kriss,  Journ.  Dairy  Science,  1926,  9,  p.  18. 


60 


METABOLISM  OF  THE  FASTING  STEER 


Influence  of  Short  Fasts  at  a  Maintenance  Level  of  Nutrition 

In  view  of  the  diversity  found  in  the  losses  in  weight  of  these  animals 
under  different  conditions  of  fasting,  i.  e.,  after  pasture,  after  maintenance 
feeding,  and  after  submaintenance  feeding,  it  is  of  importance  to  note  what 
would  be  the  actual  body-loss  in  a  series  of  fasts  where  the  feeding  con¬ 
ditions  prior  to  fasting  would  be  practically  identical  throughout  the  entire 
series.  In  connection  with  a  series  of  short  fasting  experiments  made  pri- 

Table  13. — Daily  changes  in  body-weight  on  feed  and  during  short  fasts  at  a  maintenance  level 

of  nutrition 


Steer  and  dates  of 
fasts  (1923) 

Initial 

body- 

weight 

Final 

body- 

weight 

Changes  in  weight  on  days 
before  fast 

Changes  in  weight 
on  fasting  days 

Total 
loss  in 
body- 
weight 

3 

2 

1 

1 

2 

Steer  C 

kg. 

kg. 

kg. 

kg. 

kg. 

kg. 

kg. 

kg. 

Jan. 

3  to 

6. . . 

689.8 

658.8 

— 

4.0 

+ 

4 

0 

— 

5 

4 

-24 

0 

>-  2 

8 

31.0 

Jan. 

15 

17.  . . 

686.4 

654.2 

— 

6.6 

+ 

4 

6 

— 

8 

2 

-29 

6 

-  2 

6 

32.2 

Jan. 

21 

23... 

692.8 

661.4 

+  12.6 

+ 

2 

2 

— 

4 

6 

-29 

0 

-  2 

4 

31.4 

Jan. 

28 

30. . . 

701.2 

670.6 

+  16.6 

— 

6 

8 

4* 

1 

2 

-26 

6 

-  4 

0 

30.6 

Feb. 

5 

7. . . 

700.2 

670.4 

— 

5.6 

— 

0 

2 

+ 

3 

0 

-25 

2 

-  4 

6 

29.8 

Feb. 

11 

13. .  . 

695.4 

667.0 

+  10.2 

+ 

5 

4 

— 

5 

8 

-25 

0 

-  3 

4 

28.4 

Feb. 

18 

20. .  . 

696.8 

667.2 

— 

0.4 

— 

2 

2 

+ 

3 

2 

-25 

4 

-  4 

2 

29.6 

Mar. 

1 

3. . . 

700.0 

670.2 

— 

4.0 

+ 

4 

8 

— 

2 

0 

-26 

8 

-  3 

0 

29.8 

Mar. 

8 

10. .  . 

702.0 

673.8 

+ 

1.4 

— 

1 

8 

+ 

1 

2 

-27 

0 

-  1 

2 

28.2 

Mar. 

15 

17.  . . 

703.8 

674.0 

+ 

1.4 

— 

6 

0 

+ 

0 

8 

-27 

0 

-  2 

8 

29.8 

Mar. 

22 

24. . . 

679.0 

644.2 

— 

1.4 

— 

5 

4 

— 

6 

0 

-30 

8 

-  4 

0 

34.8 

Steer  D 

* 

Jan. 

9  to 

12.  .  . 

695.0 

662.6 

+ 

2.8 

2  —  22 

8 

+  19 

2 

-26 

0 

»-  2 

2 

32.4 

Jan. 

17 

19. . . 

695.0 

659.4 

— 

0.4 

— 

9 

4 

+ 

2 

2 

-29 

2 

-  6 

4 

35.6 

Jan. 

25 

27.  .. 

694.4 

661.2 

+ 

7.8 

— 

9 

8 

+ 

5 

4 

-27 

0 

-  6 

2 

33.2 

Feb. 

1 

3. . . 

686.4 

649.6 

— 

5.4 

— 

5 

0 

+ 

2 

8 

-35 

0 

-  1 

8 

36.8 

Feb. 

8 

10. . . 

685.2 

658.4 

± 

0.0 

— 

7 

8 

— 

5 

6 

-24 

8 

—  2 

0 

26.8 

Feb. 

14 

16.  . . 

701.8 

664.6 

+  15.0 

+ 

0 

8 

— 

3 

4 

-26 

0 

-ii 

2 

37.2 

Feb. 

22 

24.  .  . 

701.0 

663.6 

— 

2.4 

— 

5 

6 

+ 

9 

4 

-27 

4 

-10 

0 

37.4 

Mar. 

5 

7.  .  . 

696.0 

661.0 

+ 

1.4 

+ 

1 

8 

+ 

1 

6 

-25 

2 

-  9 

8 

35.0 

Mar. 

13 

15. . . 

695.4 

669.6 

— 

8.4 

+ 

0 

8 

— 

5 

0 

-24 

8 

-  1 

0 

25.8 

Mar. 

20 

22.  .. 

693.8 

656.4 

+ 

0.4 

9 

4 

3 

0 

-30 

6 

-  6 

8 

37.4 

1  In  this  experiment  the  steer  fasted  3  days.  During  the  third  day,  steers  C  and  D  each 
lost  4.2  kg.  in  body-weight. 

1  The  afternoon  feed  was  withheld  on  this  day,  as  it  was  planned  to  measure  the  standard 
metabolism  the  next  morning,  but  the  experiment  was  not  made. 

marily  to  study  the  influence  of  environmental  temperature  upon  metabo¬ 
lism,  the  two  animals,  C  and  D,  were  fed  practically  a  constant  ration  for 
several  months,  receiving  9  kg.  of  hay  and  2  kg.  of  meal  daily  from  Novem¬ 
ber  20,  1922,  until  March  27,  1923.  During  this  time  they  were  subjected 
at  different  times  to  short  2-day  fasts,  and  on  one  occasion  to  a  3-day  fast. 
The  data  for  the  initial  and  the  final  body-weight,  the  total  loss  in  weight, 
and  the  changes  in  body-weight  on  the  three  days  with  food  before  the  fast 
and  on  the  several  days  of  fasting,  are  incorporated  in  Table  13.° 


°  In  Table  13  the  change  in  weight  during  the  last  24-hour  period  of  fasting  and  the  live  weight 
at  the  end  of  the  fast  have  been  corrected  for  the  first  feed  after  the  fast,  consumed  usually 
during  the  last  3  hours  of  the  24  hours,  but  in  two  cases  consumed  during  the  la6t  6  hours. 


BODY-WEIGHT 


61 


The  changes  in  body-weight  before  fasting  show  the  usual  fluctuations 
noted  in  Table  12,  and  are  due  probably  to  changes  in  water-content  and  to 
irregularity  in  the  expulsion  of  feces.  The  losses  in  weight  on  the  first  day 
of  fasting  are  remarkably  uniform  with  both  animals,  explainable  undoubt¬ 
edly  by  the  fact  that  the  feed-level  prior  to  the  fasts  was  uniform  in  all 
instances,  and  also  by  the  fact  that  in  every  instance  no  water  was  drunk 
at  the  beginning  of  the  first  fasting  day.  Thus,  with  steer  C  the  loss  in 
weight  on  the  first  day  ranges  only  from  24  to  30.8  kg.  In  the  case  of  steer 
D  the  loss  on  the  first  day  ranges  from  24.8  to  35.0  kg.  In  general,  the  uni¬ 
formity  of  ration  has  resulted  in  a  strikingly  uniform  body-loss  on  the  first 
day,  amounting  on  the  average  to  27  kg.  with  both  steers.  There  are  obvi¬ 
ously  no  instances  of  plus  values,  and  the  wide  discrepancies  noted  in 
Table  12  here  disappear.  On  the  second  day  there  is  a  pronounced  drop  in 
the  loss  to  a  level  of  not  far  from  3  to  4  kg.  in  the  case  of  steer  C,  but  in  the 
case  of  steer  D  the  change,  although  pronounced,  is  not  so  regular,  since 
the  loss  ranges  from  1.0  kg.  to  as  high  as  11.2  kg.,  being  on  the  average 
about  6  kg.  This  decrease  in  the  loss  and  the  difference  between  steers  C 
and  D  on  the  second  day  may  be  partly  explained  by  the  fact  that  steer  C 
drank  water  in  every  instance  at  the  beginning  of  the  second  day,  but  steer 
D  drank  only  in  the  case  of  the  first  five  fasts  and  the  last  two  fasts. 

In  the  long  fasts  at  different  feed-levels,  reported  in  Table  12,  the  losses 
on  the  second  day  were  very  irregular  and  much  higher  than  in  these  1923 
fasts,  particularly  with  steer  C.  There  are  three  explanations  for  this.  In 
the  first  place,  the  ration  preceding  each  of  the  short  fasts  in  1923  was  the 
same,  whereas  the  feed-levels  preceding  the  longer  fasts  varied  greatly.  In 
the  second  place,  the  second  day  of  fasting  in  the  short  fasts  began  exactly 
30  hours  after  the  last  feed  in  every  case,  and  the  amount  of  the  last  feed 
was  always  essentially  the  same.  In  the  long  fasts,  on  the  contrary,  the 
second  day  did  not  begin  the  same  number  of  hours  after  the  last  feed  in 
every  case,  the  time  varying  from  22  to  32  hours  after  the  last  feed.  More¬ 
over,  the  last  individual  feed  preceding  these  long  fasts  varied  greatly  in 
amount  and  character.  Furthermore,  there  was  greater  irregularity  in  water 
intake  on  the  second  day  of  the  longer  fasts. 

There  was  one  3-day  fast  with  each  animal  in  the  1923  series,  in  which  by 
chance  the  weight-loss  of  both  steers  was  actually  the  same  on  the  third 
day,  namely,  4.2  kg.  This  loss  is  lower,  as  a  matter  of  fact,  than  any  of  the 
other  values  found  on  the  third  day  with  these  animals  in  the  longer  fasts, 
save  in  the  case  of  the  November  1922  fast  of  steer  C  and  the  January  1922 
fast  of  steer  D. 

Aside  from  the  first  fast  in  1923,  which  was  3  days  long,  the  animals  as 
a  rule  fasted  about  51%  hours,  so  that  the  total  losses  are  comparable.  In 
51%  hours  the  total  loss  in  weight  of  steer  C  during  these  short  fasts  aver¬ 
aged  30  kg,  and  the  total  loss  of  steer  D  averaged  34  kg.  Again  a  much 
greater  regularity  was  exhibited  by  steer  C  than  by  steer  D. 


62 


METABOLISM  OF  THE  FASTING  STEER 


Losses  in  Body-weight  During  4-Day  Fasts  under  Similar  Conditions 

The  losses  noted  during  a  series  of  4-day  fasts  in  April  and  May  1924, 
when  the  animals  remained  inside  the  respiration  chamber  for  three  out  of 
the  four  days,  are  recorded  in  Table  14.  Prior  to  these  fasts  all  four  animals 
had  been  upon  a  reasonably  uniform  nutritive  plane  for  from  4  to  8  weeks. 
They  were  placed  in  the  respiration  chamber  after  having  been  24  hours 
without  food,  and  were  left  there  for  3  consecutive  days.  The  body- weights 
were  determined  only  at  the  beginning  and  end  of  the  respiration  experi¬ 
ments,  and  hence  the  data  are  available  only  for  the  total  loss  in  weight  in 
3  days  instead  of  the  losses  during  four  individual  24-hour  periods,  i.  e.,  the 
first  day’s  loss  was  not  obtained. 


Table  14. — Losses  in  body-weight  during  S  days 1  of  fasting  under  similar  conditions 


Steer 

Dates  of  fasts 

Body- 
weight  in 
November 
1923 

Body- 
weight  at 
beginning 
of  fast1 

Body- 
weight  at 
end  of 
fast 

Total 
loss  in 
body- 
weight 

1924 

kg. 

kg. 

kg. 

kg. 

F 

Mar.  31  to  Apr.  4 . 

291.0 

295.2 

271.8 

-23.4 

E 

Apr.  8  12 . 

266.2 

280.0 

260.8 

-19.2 

C 

Apr.  22  26 . 

723.8 

669.6 

620.0 

-49.6 

D 

May  13  17 . 

707.0 

664.6 

621.4 

-43.2 

1  Beginning  24  hours  after  food. 


The  two  young  animals,  E  and  F,  were  first  studied.  In  consideration  of 
the  fact  that  steer  F  weighed  essentially  the  same  at  the  beginning  of  his 
fast  in  April  1924  as  at  the  beginning  of  the  experimental  season,  namely, 
November  19,  1923,  and  that  previous  to  this  April  fast  he  had  been  on  a 
submaintenance  ration  for  several  months  and  had  then  fasted  6  days  in 
February,  it  can  be  seen  that,  judging  from  body-weight  alone,  he  had 
reached  his  original  condition.  But  meanwhile  he  had  grown,  and  was 
nearly  5  months  older.  In  all  probability,  therefore,  he  was  still  in  a  dis¬ 
tinctly  undernourished  condition.  Steer  E  had  also  passed  through  a  period 
of  undernutrition  and  a  5-day  fast  prior  to  his  fast  in  April  1924,  but  since 
his  weight  at  the  start  of  the  April  fast  was  somewhat  greater  than  that 
noted  at  the  beginning  of  the  season,  one  would  infer  that  he  was  in  a  some¬ 
what  better  nutritive  state  than  steer  F.  The  two  large  animals,  C  and  D, 
weighed  noticeably  less  than  at  the  beginning  of  the  season  on  November 
5, 1923,  when  they  came  off  pasture,  having  been  through  a  prolonged  period 
of  undernutrition  and  a  10-day  fast  previous  to  their  fasts  in  April  and  May 
1924.  Hence  they  were  distinctly  below  par  at  the  time  of  these  particular 
experiments. 

In  these  4-day  fasts  the  younger  steers,  E  and  F,  lost  19.2  and  23.4  kg., 
respectively,  and  the  older  and  larger  steers,  C  and  D,  lost  49.6  and  43.2 
kg.,  respectively.  Little  is  to  be  gained  by  attempting  to  apportion  these 
losses  over  the  four  days  and  compare  them  with  the  losses  during  the  two 
days  in  the  short  fasting  experiments,  or,  indeed,  with  the  individual  days  in 
the  prolonged  fasting  experiments.  The  chief  point  illustrated  by  these 
4-day  fasts  is  that  under  essentially  uniform  treatment  the  two  animals  in 


LOSS  THROUGH  THE  LUNGS  AND  SKIN 


63 


each  pair  are  fairly  close  physiological  duplicates.  It  is  impracticable  to 
attempt  to  compare  the  weight-losses  of  various  animals  during  fasting 
unless  experiments  follow  the  same  rationing  and  unless  the  withholding  of 
food  is  made  at  exactly  the  same  time,  the  last  feed  having  been  of  the 
same  amount.  If  duplicate  experiments  are  made  under  these  conditions, 
the  body-weight  tables  indicate  that  a  reasonably  close  physiological  dupli¬ 
cation  may  be  expected  with  two  animals  of  the  same  size  and  age,  receiving 
the  same  character  and  amount  of  feed. 

General  Conclusion  with  Regard  to  Significance  of  Changes  in 

Body-weight 

From  the  analysis  of  the  changes  in  body-weight,  not  only  during  the 
long  fasts  but  likewise  during  the  2-day  fasts  and  during  the  consecutive 
3-day  experiments  inside  the  respiration  chamber,  it  is  clear  that  the  changes 
in  body-weight  vary  greatly  with  respect  to  the  animals,  the  different  days 
of  fasting,  and  the  different  fasts.  It  has  already  been  seen  that  some  of 
the  major  differences  are  explained  by  differences  in  water  intake  and,  to  a 
much  less  degree,  by  differences  in  the  output  of  feces  or  urine.  In  each  of 
the  first  four  long  fasts  the  total  loss  in  weight  of  steer  D  was  much  les3 
than  that  of  steer  C.  If  one  considers  that  the  water  drunk  during  each  of 
these  fasts  offsets  a  theoretical  further  loss  which  would  have  been  recorded 
on  the  scales,  and  if  one  adds  the  total  amount  of  water  consumed  to  the 
total  loss  in  weight  in  each  case,  one  finds  that  the  differences  between  the 
two  animals  practically  disappear.  A  careful  study  of  the  amounts  of 
water  consumed  on  the  different  fasting  days,  the  weights  of  urine  and 
feces,  and  particularly  the  insensible  perspiration,  makes  it  evident  that  the 
differences  in  live  weights  themselves  are  wholly  without  significance  unless 
the  changes  in  these  other  factors  are  taken  into  consideration.  The  use 
of  live  weight  as  an  index  of  gain  or  loss  in  body-tissue  is,  therefore,  clearly 
ruled  out. 

LOSS  THROUGH  THE  LUNGS  AND  SKIN 

As  early  as  in  the  observations  of  Sanctorius0  and  thereafter  in  the  obser¬ 
vations  of  Bischoff6  and  of  Bischoff  and  Voit,c  and  of  Grouven,d  varying 
degrees  of  importance  were  attached  to  the  loss  through  the  lungs  and  skin 
of  an  animal  used  for  experimental  research.  Sanctorius  especially  laid 
great  stress  upon  this  loss,  which  he  determined  in  his  own  case  by  sitting 
upon  a  chair  suspended  from  a  steelyard  and  noting  his  loss  in  weight  from 
hour  to  hour  under  various  conditions  of  bodily,  mental,  and  digestive 
activity.  These  determinations  were  the  basis  of  a  large  number  of 
aphorisms  published  by  him.  When  quantitative  methods  in  studying  food 
ingestion  and  the  excretion  of  urine  and  feces,  and  particularly  when  Henne- 
berg’s  schematic  conception  of  the  animal  body  began  to  be  applied,  appar¬ 
ently  the  significance  of  the  loss  through  the  lungs  and  skin  was  disregarded. 

“  Sanctorius,  Medicina  Statica,  1614;  translated  by  John  Quincy,  London,  2d  ed.,  1720. 

b  Bischoff,  Der  Harnstoff  als  Maass  des  Stoffwechsels,  Giessen,  1853. 

e  Bischoff  and  Voit,  Die  Gesetze  der  Ernahrung  des  Fleischfressers  durch  neue  Untersuchungen, 
Leipzig  and  Heidelberg,  1860. 

d  Grouven,  Physiologisch-chemische  Fiitterungsversuche.  Zweiter  Bericht  liber  die  Arbeiten 
der  agrikulturchemischen  Versuchsstation  zu  Salzmiinde,  Berlin,  1864. 


64 


METABOLISM  OF  THE  FASTING  STEER 


Since  recent  researches  at  the  Nutrition  Laboratory0  on  humans  have  indi¬ 
cated  that  there  is  a  reasonably  close  correlation  between  insensible  loss  and 
general  metabolism,  a  special  effort  was  made  in  studying  these  steers  to 
secure  the  data  for  the  accurate  computation  of  the  insensible  loss. 

The  daily  changes  in  gross  live  weight  of  a  steer,  especially  during  fasting, 
have  little  direct  quantitative  significance,  because,  as  has  just  been  empha¬ 
sized,  they  are  profoundly  affected  by  the  amount  of  water  consumed  and 
the  feces  and  urine  passed.  If  1  kg.  of  water  is  taken  into  the  mouth  and  is 
subsequently  excreted  in  the  urine,  it  plays  practically  no  role  in  the 
metabolism  of  the  animal.  Similarly,  if  there  are  100  kg.  of  ballast  or  fill 
in  the  intestinal  tract  of  a  ruminant  at  the  beginning  of  a  fast  and  40  or  50 
kg.  of  this  fill  are  excreted  as  feces,  this  again  has  no  particular  bearing  upon 
the  metabolism  of  the  animal.  The  insensible  loss  through  the  lungs  and 
skin  does  play  a  role  in  the  metabolism,  however,  for  through  the  lungs  and 
skin,  chiefly  through  the  lungs,  passes  the  carbon  dioxide  formed  in  the 
process  of  oxidation.  The  total  weight  of  carbon  dioxide  is  not  wholly 
derived  from  body-tissue,  for  the  oxygen  comes  from  the  oxygen  in  the  air, 
but  the  carbon  of  the  carbon  dioxide  does  represent  true  body-loss.  The 
amount  of  carbon  excreted  can  be  computed,  provided  that  the  total  carbon- 
dioxide  output  is  measured  either  during  24  hours  inside  of  a  respiration 
chamber  or  in  several  periods  throughout  the  day  representative  of  the 
entire  day.  The  water  given  off  from  the  skin  doubtless  existed  in  large 
part  as  preformed  water,  but  in  the  process  of  oxidation,  particularly  of 
fat,  water  is  formed  in  which  each  gram  of  hydrogen  requires  8  grams  of 
oxygen,  which  it  gets  from  the  air.  Furthermore,  in  the  oxidation  of  carbo¬ 
hydrates  there  is  a  certain  amount  of  water  of  chemical  constitution,  namely, 
the  hydrogen  and  oxygen  of  the  molecule,  which  exists  in  the  proper  propor¬ 
tion  to  form  water.  In  the  insensible  loss  from  the  lungs  and  skin,  there¬ 
fore,  the  most  important  factor  bearing  upon  the  metabolism  is  the  carbon 
of  carbon  dioxide.  The  water  given  off  is  not,  however,  without  significance 
in  connection  with  metabolism,  for  it  represents  a  method  of  heat-loss,  each 
gram  of  water  thus  vaporized  from  the  lungs  and  skin  requiring  0.586 
calorie  for  its  vaporization. 

The  insensible  loss,  therefore,  is  made  up  of  the  carbon  of  the  fat,  protein, 
and  carbohydrate  burned  in  the  body  and  the  organic  hydrogen  and  oxygen 
preexisting  in  these  molecules,  and,  in  addition,  it  is  made  up  of  the  very 
large  and  variable  factor  of  water  vaporized  through  the  lungs  and  skin.  An 
analysis  of  the  nature  of  the  insensible  perspiration  is  of  great  physiological 
importance.  Prior  to  such  an  analysis,  however,  it  is  advisable  to  know  the 
actually  measured  insensible  loss  of  these  steers  and  to  note  whether  it  has 
any  relationship  to  feed  or  to  lack  of  feed,  activity,  and  other  factors  which 
are  known  to  affect  heat-production,  i.  e.,  the  vaporization  of  water  and  the 
production  of  carbon  dioxide. 

°  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  203,  1915,  p.  84;  Benedict  and  Hendry,  Boston  Med. 
and  Surg.  Journ.,  1921,  184,  pp.  217,  257,  282,  297,  and  329;  Benedict,  Boston  Med.  and  Surg. 
Journ.,  1923,  188,  p.  127;  Benedict,  Bull.  Soc.  Sci.  d’Hygiene  Alimen.,  1923,  11,  p.  343;  Benedict, 
Schweiz,  med.  Wochenschr.,  1923,  53,  p.  1101;  Benedict,  The  correlation  between  perspiratio 
insensibilis  and  total  metabolism,  Collection  of  articles  dedicated  to  the  seventy-fifth  birthday  of 
Professor  I.  P.  Pawlow,  published  from  the  Institution  of  Experimental  Medicine  in  Leningrad, 
1924,  p.  193;  Benedict  and  Root,  Arch.  Intern.  Med.,  1926,  38,  p.  1. 


LOSS  THROUGH  THE  LUNGS  AND  SKIN 


05 


The  data  for  computing  the  insensible  loss  must  include  accurate  weigh¬ 
ings  of  food  and  water  intake,  feces,  urine,  and  live  body-weight.  The 
quantity  of  water  drunk  by  the  animal  should  be  recorded  with  particular 
care,  since  the  variations  in  the  amount  of  water  consumed  at  different  times 
are  much  greater  than  the  variations  in  the  food  consumed  or  in  the  excre¬ 
tion  of  urine  and  feces  from  day  to  day.  All  of  these  measurements  must 
be  made  in  definite  periods,  so  that  the  computation  of  the  insensible  loss 
may  represent  the  loss  during  a  known  length  of  time.  For  this  purpose  the 
steers  were  kept  in  metabolism  stalls.  The  routine  was  to  weigh  the  animal 
each  day  at  exactly  the  same  time  (i.  e.,  representing  a  24-hour  period),  at 
which  time  the  urine  bottles  and  feces  containers  were  removed,  and  clean, 
previously  weighed  receptacles  substituted.  The  animal  was  then  at  once 
allowed  to  drink  and  the  amount  consumed  was  doubly  checked  by  noting 
both  the  loss  in  weight  of  the  water  container  and  the  gain  in  weight  of  the 
animal.  The  food  was  always  given  in  carefully  weighed  portions,  usually 
twice  during  the  24-hour  period,  about  4  p.  m.  and  7  or  8  a.  m.  Under 
these  conditions  all  the  data  are  at  hand  for  computing  exactly  the  insensible 
loss  during  a  24-hour  period.  Thus,  to  the  initial  weight  of  an  animal  on 
a  given  date  at  2  p.  m.  is  added  the  weight  of  food  and  water  consumed 
during  the  ensuing  24  hours.  To  the  weight  of  the  animal  at  the  end  of  the 
24  hours  is  added  the  weight  of  feces  and  urine  passed  during  the  24  hours. 
This  sum  is  subtracted  from  the  sum  of  the  initial  body-weight,  water,  and 
food,  and  the  difference  represents  the  insensible  loss. 

In  computing  this  loss  the  exact  times  when  food  and  water  are  consumed 
and  feces  and  urine  are  excreted  must  be  known.  Only  too  frequently 
experimental  data  are  recorded  in  such  a  manner  that  it  is  impossible  to 
subdivide  the  weights  of  urine,  feces,  and  food,  and  credit  them  to  the 
proper  24-hour  periods,  and  although  all  the  weights  may  represent  24-hour 
periods,  they  do  not  invariably  represent  the  same  24  hours.  In  our  earlier 
report  on  undernutrition  in  steers0  we  found  to  our  chagrin  that  in  many 
instances  our  own  data  did  not  fulfill  the  above  specifications,  and,  profiting 
by  this  experience,  we  attempted  to  have  the  data  in  this  report  uncon¬ 
taminated  by  such  errors.  Even  with  all  the  precautions  just  mentioned, 
however,  gross  errors  are  occasionally  found  that  are  extremely  annoying. 
It  is  hoped  in  the  future  to  have  every  weighing  doubly  checked,  and  thus 
rule  out,  if  possible,  any  errors  of  this  type.  An  inherent  difficulty  in  study¬ 
ing  the  insensible  loss  of  these  large  animals  is  the  weighing  of  the  animal 
itself.  To  determine  the  live  weight  of  an  animal  weighing  700  kg.  to  within 
0.1  per  cent  is  very  difficult.  The  scales  (see  p.  55  for  description)  were 
reasonably  accurate,  but  it  required  all  the  skill  of  the  technician  to  secure 
accurate  weights.  It  is  seriously  to  be  questioned  whether  it  is  right  to 
report  the  live  weights  any  more  closely  than  to  within  the  nearest  half 
kilogram.  Obviously,  the  weights  of  water,  feed,  feces,  and  urine  can  be 
obtained  to  within  10  grams. 

°  Benedict  and  Ritzman,  Carnegie  Inst.  Waah.  Pub.  No.  324,  1923,  p.  85. 


66 


METABOLISM  OF  THE  FASTING  STEER 


Insensible  Perspiration  During  Food  Periods  and  During  24  Hours 

Without  Food 

Inasmuch  as  a  study  of  the  insensible  loss  of  large  ruminants  has  not  been 
presented,  so  far  as  we  are  aware,  since  the  days  of  Grouven,  it  seems  justi¬ 
fiable  to  discuss,  first,  some  of  the  data  regarding  the  insensible  loss  of  our 
steers  when  on  feed  before  considering  the  losses  during  fasting.  Frequently 
during  the  4  years’  study  of  these  animals  the  so-called  “standard  metabo¬ 
lism,”  24  hours  after  the  last  feed,  was  determined  with  the  respiration 
chamber.  In  Table  15  are  recorded  the  insensible  losses  of  steers  C,  D,  E, 
and  F  for  those  days  when  the  standard  metabolism  was  measured.  In 
addition,  the  losses  are  given  for  the  three  days  prior  to  these  standard 
metabolism  experiments,  when  the  steers  were  receiving  food  daily  at  a 
nutritive  level  which  had  prevailed  for  some  time.  The  loss  on  the  day  of 
the  standard  metabolism  measurement  in  every  case  represents  the  loss 
during  the  first  24  hours  without  food,  although  in  most  instances  the  animal 
was  fed  just  before  the  end  of  the  24  hours. 

The  variability  in  the  insensible  loss  at  the  times  of  the  different  experi¬ 
ments  is  very  pronounced.  In  the  case  of  steer  C,  the  values  for  the 
insensible  loss  noted  3  days  before  the  standard  metabolism  experiments 
range  from  3.8  to  15.6  kg.  Similar  ranges  in  the  losses  occur  2  days  and  one 
day  prior  to  the  experiments.  On  the  days  of  the  standard  metabolism 
experiments,  when  the  animal  had  usually  been  without  food  for  the  entire 
24  hours,  the  range  is  somewhat  smaller,  i.  e.,  from  2.2  to  12.8  kg.,  and  the 
deviation  from  an  average  value  is  obviously  somewhat  lessened,  due  prob¬ 
ably  in  large  part  to  the  entire  lack  of  food.  With  steer  D  wider  differences 
are  noted,  the  loss  ranging  from  4.4  to  14.4  kg.,  3  days  before  the  metabo¬ 
lism  experiment,  from  4.2  to  18.4  kg.,  2  days  before,  from  4.6  to  18.4  kg.  on 
the  day  before,  and  from  3.6  to  17.6  kg.  on  the  day  of  the  experiment  itself. 
With  the  smaller  steers,  E  and  F,  the  variability  is  naturally  much  less,  the 
widest  range  during  the  food  days  in  the  case  of  steer  E  being  only  from 
2.6  to  9.4  kg.,  while  on  the  day  of  the  standard  metabolism  experiment  the 
range  is  only  from  2.4  to  7.0  kg.  With  steer  F  the  picture  is  essentially  the 
same. 

The  general  picture  of  the  range  in  daily  losses  is  that  there  are  gross 
differences  in  the  insensible  loss  at  different  times  of  the  year.  A  closer 
examination  of  the  data  in  Table  15,  however,  shows  that  on  any  three  suc¬ 
cessive  days  under  the  same  feeding  conditions  the  loss  remains  reasonably 
uniform,  and  that  on  the  days  of  standard  metabolism  experiments,  when 
food  is  withheld,  the  loss  usually  decreases  noticeably. 

The  large  differences  in  the  insensible  perspiration  noted  in  Table  15  are 
in  large  part  explained  by  the  differences  in  the  feed-level.  When  steers  C 
and  D  were  on  a  realimentation  or  a  maintenance  feed-level,  the  insensible 
perspiration  was  almost  invariably  considerably  higher  than  when  they 
were  on  a  submaintenance  feed-level.  For  example,  in  the  case  of  steer  C 
the  return  to  maintenance  feeding  on  June  18,  1923,  immediately  resulted 
in  a  marked  increase  in  the  insensible  perspiration.  This  same  picture  is 
likewise  noted  with  steer  D.  It  is  not  clear,  however,  that  the  insensible 
perspiration  is  absolutely  uniform  from  day  to  day  even  upon  the  same 


LOSS  THROUGH  THE  LUNGS  AND  SKIN 


67 


Table  15. — Daily  insensible  loss  during 


S  days  with  food,  followed  by  1  day  without  food1 


Steer  and  date  of  standard  metab¬ 
olism  experiment 

Food- 

level1 

Days  (on  food)  before  standard 
metabolism  experiment 

Day  of 
experi¬ 
ment* 

3 

2 

1 

Steer  C: 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

kg 

°  C. 

Dec. 

17, 

1921 . 

R 

3.8 

18 

3.2 

5 

3.8 

15 

4.8 

21 

Dec. 

22, 

1921 . 

R 

4.6 

12 

5.0 

20 

8.0 

13 

2.2 

7 

Jan. 

23, 

1922 . 

R 

9.4 

14 

10.4 

19 

12.4 

18 

6.4 

12 

Mar. 

31, 

1922 . 

M 

9.6 

18 

9.0 

17 

11.0 

19 

7.4 

20 

May 

9, 

1922 . 

R 

7.4 

19 

8.0 

19 

8.0 

18 

5.2 

18 

Dec. 

13, 

1922 . 

M 

11.5 

24 

13.8 

20 

14.4 

23 

9.0 

18 

Dec. 

18, 

1922 . 

M 

15.6 

27 

14.6 

24 

16.0 

26 

12.8 

26 

Dec. 

21, 

1922 . 

M 

12.8 

26 

14.2 

23 

13.4 

24 

9.4 

22 

Dec. 

26, 

1922 . 

M 

13.8 

21 

16.6 

27 

12.8 

20 

11.2 

26 

Dec. 

29, 

1922 . 

M 

11.2 

26 

15.2 

28 

11.4 

22 

6.6 

15 

Apr. 

3, 

1923 . 

M 

9.0 

12 

9.4 

10 

8.4 

13 

9.6 

21 

Apr. 

11, 

1923 . 

M 

11.2 

17 

7.8 

12 

10.8 

16 

6.4 

14 

Apr. 

18, 

1923 . 

M 

9.4 

13 

10.2 

15 

10.4 

15 

8.2 

18 

Apr. 

24, 

1923 . 

M 

15.2 

24 

14.8 

24 

9.6 

14 

6.0 

12 

May 

5, 

1923 . 

S 

6.8 

18 

5.6 

18 

7.6 

21 

7.2 

22 

May 

11, 

1923 . 

s 

6.6 

20 

7.2 

20 

6.4 

16 

4.4 

16 

May 

18, 

1923 . 

s 

5.8 

19 

5.8 

19 

8.8 

24 

5.2 

18 

May 

24, 

1923 . 

s 

5.4 

21 

5.2 

18 

5.8 

17 

4.4 

17 

June 

18, 

1923 . 

M 

11.4 

20 

9.6 

18 

12.8 

20 

7.4 

20 

Steer  D: 

Dec. 

17, 

1921 . 

R 

4.4 

18 

4.2 

5 

4.6 

17 

6.8 

21 

Dec. 

22, 

1921 . 

R 

6.4 

12 

6.0 

20 

7.8 

13 

3.6 

7 

Jan. 

23, 

1922 . 

R 

8.2 

14 

10.8 

19 

11.0 

18 

6.2 

12 

Mar. 

31, 

1922 . 

M 

9.2 

18 

8.6 

17 

9.8 

19 

6.8 

20 

May 

9, 

1922 . 

R 

5.8 

19 

7.2 

19 

6.6 

18 

5.6 

18 

Dec. 

15, 

1922 . 

M 

14.4 

23 

12.0 

18 

16.0 

24 

13.0 

27 

Dec. 

19, 

1922 . 

M 

12.6 

24 

15.6 

26 

16.6 

26 

11.8 

23 

Dec. 

22, 

1922 . 

M 

11.8 

23 

11.4 

24 

12.8 

22 

9.6 

22 

Dec. 

30, 

1922 . 

M 

12.6 

28 

10.8 

22 

8.8 

15 

17.6 

13 

Jan. 

3. 

1923 . 

M 

7.2 

11 

12.8 

15 

9.8 

12 

6.2 

11 

Apr. 

4, 

1923 . 

M 

8.8 

10 

9.4 

13 

14.6 

21 

6.6 

18 

Apr. 

12, 

1923 . 

M 

7.6 

12 

13.8 

16 

7.6 

14 

7.8 

14 

Apr. 

19, 

1923 . 

M 

9.2 

15 

8.4 

15 

9.2 

18 

6.4 

14 

Apr. 

25, 

1923 . 

M 

13.2 

24 

9.8 

14 

6.8 

12 

9.0 

20 

May 

4, 

1923 . 

s 

6.6 

6.0 

18 

5.8 

18 

5.8 

21 

May 

12, 

1923 . 

S 

7.6 

20 

5.6 

16 

5.4 

16 

8.2 

24 

May 

19, 

1923 . 

s 

4.8 

19 

8.2 

24 

4.8 

18 

5.6 

21 

May 

25, 

1923 . 

s 

5.4 

18 

7.4 

17 

5.4 

17 

6.2 

22 

June 

1, 

1923 . 

s 

6.2 

20 

6  2 

18 

5.6 

19 

7.2 

19 

June 

8, 

1923 . 

s 

11.8 

28 

11.0 

27 

7.0 

22 

4.2 

18 

June 

16, 

1923 . 

M 

8.0 

16 

7.6 

18 

9.0 

20 

9.4 

18 

June 

22, 

1923 . 

M 

14.0 

27 

18.4 

30 

18.4 

30 

12.2 

26 

Steer  E: 

Nov. 

26, 

1923 . 

M 

7.2 

13 

6.8 

21 

8.6 

23 

6.4 

16 

Dec. 

3, 

1923 . 

M 

7.8 

15 

8.0 

14 

7.4 

12 

5.8 

15 

Dec. 

10, 

1923 . 

M 

8.0 

16 

6.4 

13 

9.4 

18 

6.6 

20 

Dec. 

17, 

1923 . 

M 

8.8 

15 

6.8 

13 

6.0 

14 

7.0 

14 

Dec. 

28, 

1923 . 

S 

3.0 

10 

2.6 

13 

3.8 

15 

4.6 

15 

Dec. 

31. 

1923 . 

s 

4.6 

15 

4.2 

16 

3.0 

13 

3.2 

14 

Jan. 

8, 

1924  . 

s 

2  4 

11 

3  8 

15 

2.4 

15 

Jan. 

14, 

1924 . 

s 

3  2 

12 

3.2 

14 

2.6 

Jan. 

21, 

1924 . 

s 

3.4 

14 

3.0 

18 

3.6 

11 

Jan. 

28, 

1924 . 

s 

3.0 

16 

3.4 

10 

2.6 

10 

3.0 

11 

Feb. 

4, 

1924 . 

s 

3.2 

13 

4.0 

15 

2.8 

13 

2.4 

15 

68 


METABOLISM  OF  THE  FASTING  STEER 


Table  15. — Daily  insensible  loss  during  3  days  with  food,  followed  by  1  day  without  food1 — Con. 


Steer  and  date  of  standard  metab¬ 
olism  experiment 

Food- 

level1 

Days  (on  food)  before  standard 
metabolism  experiment 

Day  of 
experi¬ 
ment* 

3 

2 

1 

Steer  F: 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

Nov. 

27,  1923 . 

M 

8.0 

21 

7.8 

23 

7.6 

16 

5.4 

18 

Dec. 

4,  1923 . 

M 

7.0 

14 

5.8 

12 

7.0 

15 

5.4 

16 

Dec. 

11,  1923 . 

M 

3  6 

13 

8.6 

18 

8.0 

18 

Dec. 

18,  1923 . 

M 

6.6 

13 

7.0 

14 

7.2 

14 

4.0 

10 

Dec. 

29,  1923 . 

S 

2.4 

13 

3.4 

15 

4.2 

15 

3.4 

16 

Jan. 

2,  1924 . 

S 

3.2 

13 

3.2 

14 

4.0 

15 

3.2 

12 

Jan. 

9,  1924 . 

S 

3.4 

15 

3.0 

15 

3.2 

15 

2.8 

18 

Jan. 

17,  1924 . 

S 

2.6 

.  . 

3.0 

15 

2.8 

16 

3.4 

18 

Jan. 

22,  1924 . 

s 

2.6 

14 

3.6 

18 

2.4 

11 

2.6 

13 

Jan. 

29,  1924 . 

s 

1  8 

10 

2.4 

10 

3.2 

18 

Feb. 

5^  1924 . 

s 

2.4 

15 

2.8 

13 

3.2 

15 

3.0 

17 

1  The  temperature  figure  at  the  right  of  each  insensible  perspiration  figure  represents  the 
stall  temperature  during  the  same  24  hours  in  which  the  insensible  perspiration  was  measured. 

*  R,  realimentation  after  fast  (steers  C  and  D,  4  to  8  kg.  hay);  M,  maintenance  level  (steers 
C  and  D,  9  kg.  hay  and  2  kg.  meal,  Dec.  13,  1922,  to  Jan.  3,  1923,  and  9  kg.  hay,  Mar.  31,  1922, 
Apr.  3-25,  1923,  and  June,  1923;  steers  E  and  F,  5  kg.  hay  and  0.68  kg.  meal);  S,  submainte¬ 
nance  level  (steers  C  and  D,  4.5  kg.  hay;  steers  E  and  F,  2.5  kg.  hay  and  0.30  kg.  meal). 

*  During  the  24  hours  represented  by  the  insensible  perspiration  recorded  for  the  day  of  the 
experiment  either  no  food  at  all  was  eaten  or  no  food  was  eaten  until  near  the  end  of  the  24 
hours. 

ration,  for  relatively  wide  differences  do  still  exist.  But  in  general,  with  the 
submaintenance  ration  the  insensible  loss  is  low  and  with  the  maintenance 
ration  it  is  high.  The  situation  is  exactly  duplicated  in  the  case  of  steers  E 
and  F,  but  since  their  body-weights  are  much  smaller,  the  insensible  per¬ 
spiration  is  naturally  smaller  than  that  of  steers  C  and  D.  Even  with  these 
two  smaller  animals,  however,  it  can  be  seen  that  on  submaintenance  rations 
the  insensible  perspiration  is  perceptibly  lower  than  on  maintenance  rations. 
Thus,  the  data  show  clearly  a  relationship  between  the  feed-level  and  the 
insensible  perspiration.  Since  it  is  known  that  with  the  higher  feed-level 
there  is  a  higher  metabolism,  this  relationship  between  the  feed-level  and 
the  insensible  loss  is  the  first  clue  that  there  is  a  relationship  between  the 
insensible  perspiration  and  the  metabolic  level.  This  latter  relationship  ha3 
been  most  carefully  studied  with  humans  and  has  been  shown  to  exist  with 
remarkable  accuracy,  indeed,  so  much  so  that  it  has  been  proposed  to  pre¬ 
dict  the  metabolism  of  humans  from  the  insensible  perspiration  carefully 
determined  under  standard  conditions.0 

In  Table  15  the  individual  figures  for  the  separate  days  have  been  given 
and  no  attempt  has  been  made  to  smooth  out  the  irregularities,  but  it  is 
clear  that  with  ruminants  the  feed-level  is  not  the  sole  factor  in  determining 
the  intensity  of  the  insensible  perspiration.  Indeed,  we  noted  early  in  the 
research  that  the  environmental  temperature  played  a  not  insignificant  role. 
Thus,  the  variations  in  the  insensible  loss  occasionally  noted  even  on  con¬ 
secutive  days,  i.  e.,  with  a  constant  feed-level,  can  be  fairly  closely  corre- 


Benedict  and  Root,  Arch.  Intern.  Med.,  1926,  38,  p.  1. 


LOSS  THROUGH  THE  LUNGS  AND  SKIN 


69 


lated,  in  most  instances,  with  large  differences  in  the  environmental  tem¬ 
perature.  Since  the  insensible  loss  is  made  up  in  large  part  of  vaporized 
water,  it  is  not  surprising  that  changes  in  environmental  temperature  affect 
the  insensible  loss,  because  of  their  effect  upon  the  vaporization  of  water 
both  from  the  lungs  and  skin.  A  full  understanding  of  the  data  in  Table  15 
can  therefore  only  be  had  by  taking  into  consideration  the  stall  tempera¬ 
tures  under  which  the  determinations  of  the  insensible  perspiration  were 
made.  The  stall  temperatures,  expressed  in  degrees  centigrade,  have 
accordingly  been  incorporated  in  the  table. 

A  comparison  of  the  insensible  losses  and  environmental  temperatures  on 
consecutive  days,  i.  e.,  with  constant  feed-level,  indicates  that  generally  the 
high  temperature  is  accompanied  by  a  relatively  high  insensible  loss.  There 
are,  however,  exceptions  to  this  with  sufficient  frequency  to  make  it  difficult 
to  draw  more  than  a  general  conclusion.  Thus,  in  the  experiment  of  Decem¬ 
ber  22,  1921,  steer  C  had  an  insensible  perspiration  of  4.6  kg.  3  days  before 
the  metabolism  test,  5.0  kg.  2  days  before,  and  8  kg.  on  the  day  before,  with 
stall  temperatures  of  12°,  20°,  and  13°  C.,  respectively.  On  the  day  of  the 
standard  metabolism  experiment  the  loss  was  but  2.2  kg.,  with  a  tem¬ 
perature  of  7°  C.  The  differences  in  temperature  and  the  fairly  even  insen¬ 
sible  perspiration  in  these  first  experiments  with  steer  C  can  be  discussed 
only  with  considerable  caution.  Since  the  first  two  experiments  with  steer 
C  were  made  during  the  realimentation  period  following  a  7-day  fast,  it 
is  not  inconceivable  that  the  insensible  perspiration  may  have  reached  a 
minimum  level  due  to  the  previous  fasting,  below  which  it  could  not  drop 
appreciably  even  with  a  marked  fall  in  temperature.  Hence  the  low  values 
of  3.2  kg.  on  the  second  day  before  the  experiment  on  December  17,  with 
a  temperature  of  5°  C.,  and  of  3.8  kg.  on  the  next  day,  with  a  rise  in  tem¬ 
perature  of  10°  C.,  may  be  explained  by  the  fact  that  the  animal  had 
already  reached  a  very  low  level  as  a  result  of  the  7-day  fast. 

The  general  picture,  however,  is  that  with  high  environmental  tempera¬ 
tures  and  a  constant  feed-level  there  appears  frequently  a  large  insensible 
loss,  which  might  be  caused  by  an  increased  vaporization  of  water  from 
the  lungs  and  skin  as  a  result  of  the  high  temperature.  Obviously,  wind 
velocity  and  humidity  should  also  be  taken  into  consideration.  When  in 
the  metabolism  stalls,  the  animals  were  not  exposed  to  drafts  and  pre¬ 
sumably  on  each  day  the  movement  of  air  was  essentially  the  same,  for  the 
laboratory  was  well  constructed,  so  that  there  was  a  minimum  amount  of 
draft.  Inside  the  respiration  chamber  the  air  was  invariably  moved,  but 
not  violently,  by  an  electric  fan,  to  insure  equalization  in  its  chemical  com¬ 
position.  The  steers  were  therefore  not  subjected  to  excessive  movement  of 
air  during  the  metabolism  experiments. 

From  this  analysis  of  the  data  in  Table  15,  the  conclusion  can  be  drawn 
that  the  insensible  loss  from  day  to  day,  under  the  same  conditions  of  feed¬ 
ing,  and  particularly  if  the  environmental  temperature  is  constant,  is  rea¬ 
sonably  uniform.  Indeed,  this  conclusion  is  substantiated  by  Grouven’s 
study  of  the  insensible  loss,  which  he  computed  to  be  astonishingly  constant 
from  day  to  day  with  animals  under  uniform  conditions  of  feed  and  tem¬ 
perature.  The  withholding  of  food,  on  the  day  of  the  standard  metabolism 


70 


METABOLISM  OF  THE  FASTING  STEER 


experiment,  results  usually  in  a  pronounced  fall  in  the  daily  insensible  loss, 
provided  that  the  temperature  conditions  remain  uniform.  Since  the  metabo¬ 
lism  is  known  to  be  lowered  as  the  result  of  the  absence  of  digestive  activity, 
it  would  appear  as  if,  in  this  respect  at  least,  the  insensible  loss  were  corre¬ 
lated  with  the  total  heat-production. 

Insensible  Loss  During  Three  Days  with  Food,  Followed  by  Two  and 

Three  Days  Without  Food,  at  a  Maintenance  Level  of  Nutrition 

In  connection  with  another  series  of  respiration  experiments  carried  out 
on  steers  C  and  D  during  short  periods  of  fasting  at  a  maintenance  feed- 
level,  records  of  the  insensible  loss  are  available  for  the  three  days  with 
food  prior  to  the  fast  and  for  each  of  the  two  or  three  days  of  fasting.  These 
records  are  given  in  Table  16,  in  which  the  first  day  of  fasting  corresponds 
exactly  with  the  day  of  the  standard  metabolism  experiment  recorded  in 
Table  15,  except  that  the  steers  were  given  no  feed  at  all  during  this  first 
day,  while  on  the  day  of  the  standard  metabolism  experiment  they  were  in 
most  cases  fed  just  before  the  end  of  the  day.  But  obviously  in  this  latter 

Table  16. — Daily  insensible  loss  during  3  days  with  food,  followed  by  2  days  without  food 


Steer  and 
dates  of 
fasts 
(1923) 

Days  before  fast 
(with  food) 

Days  fasting1 

3 

2 

1 

1 

2 

Steer  C: 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

Jan  3  to 

6! 

12.6 

15 

9.8 

12 

9.0 

11 

6.2 

6 

3.0 

9 

Jan.  15 

17 

15.2 

25 

13.4 

20 

15.6 

26 

11.8 

29 

3.0 

12 

Jan.  21 

23 

13.6 

28 

18.6 

27 

18.0 

29 

10.8 

28 

4.4 

7 

Jan.  28 

30 

8.8 

11 

16.8 

26 

9.4 

11 

4.8 

8 

5.0 

25 

Feb.  5 

7 

9.8 

12 

8.2 

4 

7.8 

7 

5.2 

6 

2.8 

5 

Feb.  11 

13 

8.2 

8 

10.2 

10 

9.2 

11 

4.6 

8 

2.8 

8 

Feb.  18 

20 

7.4 

-3 

7.2 

3 

8.0 

7 

3.4 

4 

3.6 

0 

Mar.  1 

3 

9.2 

12 

10.8 

13 

9.4 

11 

6.2 

12 

3.6 

14 

Mar.  8 

10 

6.6 

4 

8.0 

3 

7.0 

4 

4.6 

4 

3.0 

6 

Mar.  15 

17 

11.2 

9 

10.4 

7 

9.8 

5 

5.2 

8 

3.8 

8 

Mar.  22 

24 

15.2 

19 

18.8 

24 

3  20.2 

27 

14.8 

26 

8.8 

22 

Steer  D: 

Jan.  9  to 

122 * 4 

8.2 

8 

4  5.6 

11 

8.2 

12 

6.4 

13 

3.4 

9 

Jan.  17 

19 

16.4 

26 

17.8 

29 

11.2 

12 

6.0 

12 

8.2 

28 

Jan.  25 

27 

9.2 

7 

10.6 

13 

8.6 

11 

5.8 

11 

6.8 

26 

Feb.  1 

3 

16.0 

25 

18.2 

28 

16.8 

23 

12.6 

23 

3.4 

12 

Feb.  8 

10 

7.6 

6 

5.6 

5 

8.0 

7 

5.0 

8 

3.2 

10 

Feb.  14 

16 

6.8 

8 

8.2 

8 

6.8 

6 

4.6 

-3 

2.4 

-3 

Feb.  22 

24 

7.6 

0 

6.4 

6 

7.6 

6 

4.4 

2 

3.2 

-2 

Mar.  5 

7 

10.0 

14 

9.0 

11 

7.4 

5 

3.8 

4 

3.8 

3 

Mar.  13 

15 

8.2 

5 

8.8 

7 

10.2 

9 

6.0 

7 

3.8 

5 

Mar.  20 

22 

10.0 

7 

19.4 

24 

15.6 

19 

14.2 

24 

10.4 

27 

1  The  first  day  begins  at  2  p.  m.,  the  last  feed  being  given  between  7  and  8  a.  m.  The  loss 
during  the  last  day  of  fasting  may  be  influenced  by  the  first  feed  following  the  fast,  given  usually 
during  the  last  3  hours  of  the  day  (in  two  cases  given  during  the  last  6  hours). 

2  On  Jan.  6  and  12  steers  C  and  D  fasted  a  third  day,  and  the  insensible  perspiration  was  2.8  and 
3.0  kg.,  respectively. 

5  High  value  possibly  due  to  rise  in  temperature  and  limitation  of  water  consumption.  After 
Mar.  15  the  steers  were  limited  to  27  kg.  of  water  daily. 

4  Food  withheld  for  respiration  experiment,  but  experiment  not  made. 


LOSS  THROUGH  THE  LUNGS  AND  SKIN 


71 


instance  the  weight  of  feed  was  taken  into  consideration  in  computing  the 
insensible  perspiration. 

From  the  data  for  the  three  days  with  food  prior  to  the  fast,  essentially 
the  same  conclusion  may  be  drawn  as  was  drawn  from  the  data  in  Table  15, 
namely,  that  under  uniform  conditions  of  feeding  and  environmental  tem¬ 
perature  the  insensible  loss  on  three  successive  days  is  reasonably  constant. 
When  there  is  a  marked  rise  in  temperature,  the  insensible  loss  is  usually 
somewhat  increased.  On  the  first  day  of  fasting,  in  contradistinction  to  the 
results  on  the  days  of  standard  metabolism  experiments,  there  is  invariably 
a  decrease,  at  times  very  pronounced.  On  the  second  day  there  is  usually  a 
still  greater  decrease.  The  loss  on  the  first  day  of  fasting  ranges  in  the 
case  of  steer  C  from  3.4  to  14.8  kg.  and  in  the  case  of  steer  D  from  3.8  to 
14.2  kg.  This  variability  in  large  part  disappears  on  the  second  day,  the 
range  being  only  from  2.8  to  8.8  kg.  with  steer  C  and  from  2.4  to  10.4  kg. 
with  steer  D.  The  influence  of  environmental  temperature  is  well  marked. 
Thus,  on  the  second  day  of  fasting  the  two  greatest  losses  with  steer  C 
(5  and  8.8  kg.)  are  coincidental  with  the  two  highest  temperatures  (25°  and 
22°  C.),  and  with  steer  D  the  highest  temperatures  (28°  and  27°  C.)  occur 
simultaneously  with  the  two  highest  losses  (8.2  and  10.4  kg.).  In  the  one 
experiment  when  the  steers  fasted  for  3  days  the  loss  on  the  third  day  is 
essentially  that  on  the  second  day,  namely,  about  3  kg.  with  each  animal. 

In  Table  16,  due  in  large  part  to  the  fact  that  the  feed-level  was  in  all 
cases  constant,  the  evidence  is  much  more  striking  than  in  Table  15 — that 
there  is  a  regular  loss  from  day  to  day  with  uniform  conditions  of  feed  and 
environmental  temperature.  During  fasting  there  is  invariably  a  pro¬ 
nounced  decrease  in  the  insensible  perspiration  on  the  first  day  and  a  much 
greater  decrease  on  the  second  day.  The  loss  of  both  animals  is  remarkably 
uniform  throughout  the  entire  series  on  the  second  day,  except  in  the  last 
experiment  with  each  steer,  when  a  high  insensible  loss,  probably  due  to  the 
high  environmental  temperature,  was  noted. 

Insensible  Loss  During  Five  to  Fourteen  Days  without  Food 

Having  noted  the  reasonable  regularity  in  the  insensible  loss  on  succeed¬ 
ing  days  of  uniform  feed  and  environmental  temperature,  the  pronounced 
decrease  in  loss  on  the  first  day  of  fasting,  and  the  still  further  pronounced 
decrease  on  the  second  day  to  a  reasonably  uniform  loss  in  the  case  of  both 
animals  of  about  3  or  4  kg.  per  day,  we  may  pass  to  an  examination  of  the 
insensible  loss  during  longer  periods  of  fasting,  as  recorded  in  Table  17. 

In  these  longer  fasting  experiments  unusual  precautions  were  taken  to 
secure  the  greatest  accuracy  in  all  records  of  weights,  additional  student 
labor  being  employed  to  check  the  weights.  Even  with  these  precautions, 
the  record  for  steer  C  on  the  day  before  the  fast  in  December  1921  has  had 
to  be  discarded  because  of  an  obvious  error  in  recording  one  of  the  weights. 

On  the  three  successive  days  prior  to  each  fast  there  is  a  reasonable 
degree  of  uniformity  in  the  loss,  although  the  level  of  the  loss  varies  greatly 
in  the  different  experiments.  Thus,  the  average  loss  of  steer  C  for  3  days 
prior  to  the  March  1924  fast  was  6.9  kg.,  but  the  average  amount  prior  to 
the  other  fasts  was  approximately  twice  this  amount.  The  same  picture  is 
shown  in  the  losses  of  steer  D  during  the  three  days  before  the  fasts.  The 


72 


METABOLISM  OF  THE  FASTING  STEER 


Table  17. — Daily  insensible  perspiration  during  8  days  unth  food,  followed  by  5  to  14  days 

without  food 


Steer  and  dates  of  fasts 

Days  before  fast 
(with  food) 

Days  fasting 

3 

2 

1 

1 

2 

3 

Steer  C: 

kg. 

°  C. 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

rw  fi  tn  IS  1 Q21  . 

10  0 

9 

10  0 

7 

4  0 

5 

3  4 

5 

1  6 

15 

Jan.  4 

14,  1922 . 

16.0 

16 

13.8 

16 

12.0 

14 

11.6 

20 

7.0 

20 

4.8 

20 

Apr.  17 

May  1,  1922 . 

17.2 

21 

15.4 

17 

16.6 

20 

12.6 

20 

6.0 

20 

7.2 

20 

June  1 

7,  1922 . 

18.4 

24 

16.6 

22 

16.8 

23 

10.8 

23 

5.2 

22 

5.6 

23 

Nov.  6 

16,  1922 . 

12  6 

7.8 

8  0 

Nov.  4 

10’  19231 . 

6.2 

3.8 

Mar.  3 

13,  1924 . 

7.4 

13 

6.6 

16 

6.8 

17 

*2.S 

14 

1.4 

16 

2.6 

16 

Steer  D: 

Dec.  6 

to  13,  1921 . 

10.0 

9 

9.0 

7 

9.2 

7 

4.4 

5 

3.2 

5 

3.2 

15 

Jan.  4 

14,  1922 . 

17.0 

16 

15.0 

16 

16.2 

14 

11.4 

20 

7.0 

20 

5.0 

20 

Apr.  17 

May  1,  1922 . 

15.0 

21 

13.2 

17 

15.8 

20 

12.4 

20 

4.2 

20 

5.2 

20 

June  1 

6,  1922 . 

16.6 

24 

14.2 

22 

15.8 

23 

9.2 

23 

6.2 

22 

6.2 

23 

Nov.  6 

14,  1922 . 

14  0 

9  4 

8  8 

Nov.  4 

9,  19231 . 

11  6 

5  0 

Mar.  3 

12,  1924 . 

5.6 

13 

7.4 

16 

6.2 

17 

s3.0 

14 

3.4 

16 

2.8 

16 

Steer  E; 

Feb.  12  to  17,  1924 . 

3.2 

12 

2.4 

12 

3.4 

13 

3.2 

16 

1.8 

15 

2.2 

16 

Steer  F: 

Feb.  12  to  18,  1924 . 

2.8 

12 

3.0 

12 

2.0 

13 

3.6 

16 

1.2 

15 

2.2 

16 

Days  fasting 

fcteer  and  dates  oi  lasts 

4 

5 

6 

7 

8 

9 

Steer  C: 

kg. 

°  C. 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

Dec.  6  to  13.  1921 . 

3.2 

20 

2.8 

18 

2.2 

17 

2.2 

20 

Jan.  4 

14,  1922 . 

5.4 

21 

3.6 

24 

4.2 

20 

4.0 

20 

3.6 

21 

3.6 

23 

Apr.  17 

May  1,  1922 . 

2.4 

15 

3.2 

20 

4.2 

22 

3.8 

22 

3.6 

22 

4.0 

23 

June  1 

7,  1922 . 

4.6 

25 

5.0 

27 

Nov.  6 

16,  1922 . 

7.2 

3.0 

1.6 

2.4 

2.0 

4.0 

Nov.  4 

10,  19231 . 

3.0 

2.8 

Mar.  3 

13,  1924 . 

1.8 

16 

1.4 

14 

3.8 

16 

1.6 

18 

1.0 

14 

2.4 

16 

Steer  D: 

Dec.  6 

to  13,  1921 . 

3.8 

20 

3.6 

18 

2.4 

17 

3  2 

20 

Jan.  4 

14,  1922 . 

6.8 

21 

5.2 

24 

4.0 

20 

3.0 

20 

4.0 

21 

4.4 

23 

Apr.  17 

May  1,  1922 . 

4.2 

15 

3.0 

20 

3.8 

22 

3.6 

22 

3.8 

22 

4.6 

23 

June  1 

6,  1922 . 

5.2 

25 

Nov.  6 

14,  1922 . 

8.6 

3.6 

3.0 

2  6 

N  ov.  4 

9,  19231 . 

4.8 

4.0 

Mar.  3 

12,  1924 . 

2.8 

16 

2.2 

14 

2.8 

16 

4.0 

IS 

2.2 

14 

1.4 

16 

Steer  E: 

Feb.  12 

to  17,  1924 . 

2.6 

15 

Steer  F: 

Feb.  12  to  18.  1924 . 

1.8 

15 

2.2 

14 

1  Stall  temperature,  Nov.  5,  1923,  ca.  20°  C. ;  Nov.  6,  19°  C.  in  daytime,  15°  C.  at  night;  Nov. 
8,  from  ca.  20°  C.  to  12°  or  13°  C.;  daily  records  not  kept  of  stall  temperature  until  Nov.  23, 
1923. 

7  This  value  represents  a  period  of  only  17  hours,  from  2  p.  m.  to  7  a.  m. 


LOSS  THROUGH  THE  LUNGS  AND  SKIN 


73 


Table  17. — Daily  insensible  ■perspiration  during  8  days  with  food,  followed  by  5  to  14  days 

without  food — Continued 


Steer  and  dates  of  fasts 

Days  fasting 

10 

11 

12 

13 

14 

Steer  C: 

Jan.  4  to  14,  1922 . 

kg. 

4.2 

4.8 

2.0 

4.0 

3.4 

°C. 

23 

20 

16 

23 

20 

kg. 

°c. 

kg. 

°C. 

kg. 

°C. 

kg. 

°  C. 

Apr.  17  May  1,  1922 . 

Mar.  3  13,  1924 . 

2.0 

22 

3.0 

21 

3.6 

21 

3.4 

21 

Steer  D: 

Jan.  4  14,  1922  . 

Apr.  17  May  1,  1922 . 

3.2 

22 

2.8 

21 

4.2 

21 

2.8 

21 

striking  difference  between  the  loss  prior  to  the  fast  in  March  1924  and  the 
losses  prior  to  the  earlier  fasts  is  explained  by  the  fact  that  in  March  1924 
both  animals  were  upon  a  submaintenance  ration  and  were  very  much 
undernourished.  They  had  lost  in  live  weight,  to  be  sure,  but  not  in  pro¬ 
portion  to  the  decrease  in  insensible  loss.  The  losses  on  the  days  with  high 
temperatures  are,  in  general,  as  noted  earlier,  somewhat  higher  than  on  the 
days  with  low  temperatures.  Thus,  with  steer  C,  the  minimum  losses,  aside 
from  those  in  March  1924,  occur  with  temperatures  of  7°  and  9°  C.,  and  the 
maximum  losses  are  coincidental  with  temperatures  of  22°  to  24°  C.  The 
minimum  losses  of  steer  D  are  also  coincidental  with  the  low  temperatures 
of  7°  and  9°  C.,  but  the  correlation  between  the  high  temperatures  and  the 
maximum  losses  is  not  so  pronounced  as  with  steer  C.  The  low  values 
found  in  March  1924  with  both  animals  may  not  be  ascribed  to  a  low 
environmental  temperature,  for  the  temperatures  are  not  far  from  those  in 
January  and  April  1922,  when  twice  as  great  an  insensible  loss  was  noted 
with  both  animals.  Thus  the  clear  effect  of  submaintenance  feeding  is  seen. 

The  smaller  animals,  E  and  F,  were  placed  upon  a  submaintenance  ration 
prior  to  their  long  fasts.  In  their  case  there  is  considerable  uniformity  in 
the  loss  from  day  to  day  prior  to  the  fast,  the  values  for  the  two  steers 
showing  close  agreement.  The  influence  of  temperature  plays  no  role  here, 
for  essentially  the  same  temperature  was  noted  each  day. 

In  the  fasting  experiments  proper  there  is  in  all  instances  a  striking  drop 
in  the  loss  of  the  two  large  steers  on  the  first  day  of  the  fast,  but  practically 
no  change  in  the  loss  of  the  two  small  animals.  The  large  decrease  noted 
in  the  fasts  of  steers  C  and  D  following  the  submaintenance  feeding,  how¬ 
ever,  is  partly  explained  by  the  fact  that  the  first  day  of  this  fast  was  only 
17  hours  long,  instead  of  the  usual  24  hours.  The  losses  of  steers  C  and  D 
on  the  first  day  of  fasting  again  show  a  reasonably  close  correlation  with 
the  environmental  temperature,  since  the  lowest  losses  (with  the  exception 
of  the  losses  in  the  March  1924  fasts)  occur  at  the  lowest  temperature 
(5°  C.).  On  the  second  day  of  fasting  there  is  a  still  further  drop  in  the 


74 


METABOLISM  OF  THE  FASTING  STEER 


case  of  all  animals,  a  drop  which  amounts  on  the  average  to  somewhat  less 
than  50  per  cent  of  the  loss  on  the  first  day.  On  the  third  day  a  further 
drop  is  noticed  in  7  instances,  but  on  the  average  the  loss  is  not  materially 
different  on  the  third  day.  After  the  third  day,  and  more  especially  after 
the  fourth  day,  there  is  a  general  tendency  for  the  losses  to  be  not  far  from 
3  to  4  kg.,  although  occasionally  values  as  low  as  2  kg.  and  under  are  noted. 

The  uniformly  low  insensible  loss  from  the  second  day  of  fasting  to  the 
end  of  the  fast  in  the  case  of  both  steers  C  and  D  in  the  fast  following  sub¬ 
maintenance  feeding  in  March  1924  is  striking.  An  average  figure  of  2.5 
kg.  per  day  could  be  assumed  to  represent  their  daily  insensible  loss  during 
this  fast. 

A  striking  correlation  between  environmental  temperature  and  insensible 
loss,  after  the  first  few  days  of  fasting,  is  not  apparent,  although  there  are 
instances  when  low  values  appear  with  low  temperatures  and  higher  values 
with  the  higher  temperatures. 

The  variability  in  environmental  temperature  complicates  the  interpre¬ 
tation  of  the  effect  of  different  nutritive  levels,  but  nevertheless  the  evidence 
is  sufficient  to  conclude  that  the  most  potent  factor  in  determining  the  mag¬ 
nitude  of  the  insensible  perspiration  is  the  general  nutritive  plane  or 
metabolic  level.  In  other  words,  the  insensible  loss  probably  is  closely  cor¬ 
related  with  the  total  24-hour  metabolism  of  the  animal  at  the  time  the 
insensible  loss  is  measured.  To  prove  this  conclusion,  however,  24-hour 
metabolism  experiments  should  be  made  simultaneously  with  the  measure¬ 
ments  of  insensible  perspiration.  Such  simultaneous  measurements  were 
unfortunately  not  made.  In  the  3-day  metabolism  experiments  which  were 
made,  it  was  possible  to  determine  the  insensible  perspiration  only  on  the 
3-day  basis,  and  the  difficulties  of  collecting  urine  and  feces  in  a  chamber 
at  that  time  not  specially  provided  with  feces  ducts  were  such  as  to  preclude 
accurate  measurements  of  weights  of  feces  for  such  computation.  It  is 
believed,  however,  that  the  evidence  is  sufficiently  striking  to  make  it  incum¬ 
bent  upon  all  workers  who  are  studying  large  animals  in  respiration  cham¬ 
bers  permitting  24-hour  experimental  periods  to  lay  special  emphasis  upon 
collecting  the  data  for  computing  the  insensible  loss.  Changes  in  body- 
weight  from  day  to  day  during  fasting  are  only  a  very  crude  index  of  the 
change  in  body  substance.  The  insensible  loss,  on  the  other  hand,  is  more 
closely  correlated  with  the  nutritive  plane  and,  in  all  probability,  when  care¬ 
fully  measured,  bears  a  close  relationship  to  the  actual  loss  of  tissue  through 
metabolism. 

It  is  not  mere  coincidence  that  the  daily  insensible  loss  of  these  steers  was 
largest  when  they  were  on  heavy  rations.  Thus,  our  detailed  data  show 
that  when  steer  C  was  receiving  an  average  daily  ration  of  8  kg.  of  hay 
and  1.36  kg.  of  meal,  his  insensible  perspiration  was  on  the  average  9  kg. 
During  fasting  this  fell  to  an  average  of  about  2.5  kg.  Subsequently,  when 
he  was  given  7  kg.  of  hay  and  6  kg.  of  meal,  his  insensible  perspiration 
increased  to  16  kg.  on  the  average.  Even  in  the  case  of  the  small  animals, 
E  and  F,  when  they  were  receiving  an  average  ration  of  5  kg.  of  hay  and 
0.7  kg.  of  meal,  the  daily  insensible  loss  ranged  not  far  from  7  to  8  kg. 
When  the  ration  was  reduced  to  one-half,  the  loss  immediately  fell  to  not 


DRINKING-WATER 


75 


far  from  3.5  kg.  During  the  actual  fasting  experiments  this  loss  fell  still 
further,  and  with  the  resumption  of  feeding  increased. 

The  evidence,  therefore,  although  admittedly  complicated  by  the  factor 
of  environmental  temperature,  strongly  suggests  a  close  correlation  between 
the  insensible  loss  of  these  large  ruminants  and  their  nutritive  plane  or 
24-hour  metabolism.  It  is  believed  that  this  correlation  is  sufficiently  close 
to  justify  making  records  of  the  insensible  loss  as  a  part  of  the  regular 
routine  in  all  careful  metabolism  studies.  Indeed,  it  is  believed  that  the 
prediction  of  the  total  daily  metabolism  of  steers  may  actually  be  made 
with  close  approximation  if  the  insensible  loss,  under  controlled  conditions 
of  temperature,  is  accurately  known.  The  same  correlation  between  the 
insensible  loss  and  the  metabolic  activity  of  humans  has  been  frequently 
noticed  at  the  Nutrition  Laboratory,  and  its  experiments  on  this  point  have 
recently  been  reported.0 

A  series  of  measurements  of  the  insensible  loss,  made  on  animals  at  vary¬ 
ing  nutritive  planes,  but  at  a  uniform  temperature  to  rule  out  the  disturbing 
factor  of  environmental  temperature,  is  most  essential.  Apparently  with 
ruminants  the  effect  of  environmental  temperature  upon  the  insensible  loss 
may  be  much  greater  than  with  humans.  With  humans  the  insensible  loss 
may  be  considered  as  coming  from  two  sources,  from  the  lungs  and  from 
the  skin.  The  loss  from  the  skin  is  seemingly  unaffected  by  ordinary 
changes  of  temperature  (up  to  25°  C.),  wind  velocity,  and  air  movement. 
The  loss  from  the  lungs  is  in  large  part  determined  by  the  carbon-dioxide 
production  in  the  body,  i.  e.,  the  metabolism.  Indeed,  so  closely  has  this 
relationship  been  established  with  humans  that  the  measurement  of  the 
insensible  perspiration  has  been  used  as  an  index  of  the  total  metabolism. 
Undoubtedly  any  factor  affecting  total  metabolism,  such  as  activity  and 
particularly  the  nutritive  plane,  and  possibly  the  environmental  tempera¬ 
ture,  will  alter  the  insensible  loss. 

DRINKING-WATER 

When  animals  are  completely  deprived  of  food  and  water,  the  processes 
of  metabolism  in  which  katabolism  predominates  can  be  studied  in  their 
simplest  terms.  With  the  current  belief  that  water  plays  an  insignificant 
role  in  metabolism,  it  seems  at  first  sight  immaterial  whether  water  is  with¬ 
held  or  not.  Some  species  of  animals,  namely,  the  carnivora,  and  particu¬ 
larly  the  dog,  can  live  for  an  incredibly  long  time  without  water  and  food. 
Thus,  Awrorow’s  dogs  withstood  fasting,  without  water,  for  44  or  more 
days.6  But  the  fasting  metabolism  of  the  dog  involves  the  disintegration 
of  protein  and  muscle  to  such  a  large  extent  that  sufficient  water  is  released 
for  physiological  purposes.  Experience  with  other  animals,  however,  has 
shown  that  the  withdrawal  of  water  hastens  the  approach  of  severe  distress 
and  finally  death.  For  experimental  purposes  in  the  laboratory,  therefore, 
usually  food  alone  is  withheld.  Indeed,  in  all  the  fasting  experiments  made 
by  the  Nutrition  Laboratory  or  by  its  cooperative  investigators,  this  pro¬ 
cedure  has  been  followed.  Thus,  the  man  who  fasted  for  31  days  received 

0  Benedict  and  Root,  Arch.  Intern.  Med.,  1926,  38,  p.  1. 

b  Awrorow,  Metabolism  and  energy  production  of  the  organism  during  complete  fasting.  Dis¬ 
sertation,  St.  Petersburg,  1900.  (In  Russian.) 


76 


METABOLISM  OF  THE  FASTING  STEER 


from  750  to  900  c.  c.  of  distilled  water  per  day,3  and  geese  which  fasted  for 
30  days  or  more  were  invariably  allowed  to  drink  water  as  desired. 

The  consumption  of  large  amounts  of  water  by  ruminants,  especially  when 
they  are  fed  in  the  barn,  is  a  natural  consequence  of  their  eating  large 
amounts  of  highly  desiccated  feed,  such  as  hay  and  grain.  When  animals 
are  on  pasture,  the  succulent  grass  furnishes  of  itself  a  large  amount  of 
water,  but  even  this  source  of  supply  is  usually  supplemented  by  drafts  of 
water  from  time  to  time.  The  consumption  of  water  has  commonly  been 
considered  as  being  determined  to  great  extent  by  the  amount  of  food  eaten. 
Kellner* 6  assumes  that  for  each  kilogram  of  dry  matter  in  feed  about  4  kg. 

Table  18. — Daily  water  consumption  prior  to  and  during  2-day  fasts,  steers  C  and  Dl 


Steer  and  dates  of  fasts  (1923) 

Days  before  fast 

Days  fasting 

3 

2 

1 

1 

2 

3 

Steer  C: 

kg. 

kg. 

kg. 

kg. 

kg. 

kg. 

Jan.  3  to  6 . 

25.4 

28.6 

18.2 

0.0 

9.8 

6.2 

Jan.  15  17 . 

24.4 

36.0 

22.6 

0.0 

9.4 

Jan.  21  23 . 

37  4 

33.4 

29.8 

0.0 

10  4 

Jan.  28  30 . 

37.0 

26.6 

28.2 

0.0 

9.4 

Feb.  5  7 . 

21  6 

27.0 

25.8 

0.0 

9.0 

Feb.  11  13 . 

30  4 

26.8 

18.6 

0  0 

10.6 

Feb.  18  20 . 

18.4 

21.6 

27.6 

0.0 

9.6 

Mar.  1  3 . 

20.6 

30.0 

23.8 

0.0 

10.4 

Mar.  8  10 . 

21  4 

23.2 

23.8 

0  0 

10  0 

Mar.  15  17 . 

28.0 

22.2 

26.6 

0.0 

9.8 

Mar.  22  24 . 

25.8 

25.0 

26.4 

0.0 

12.4 

Steer  D: 

Jan.  9  to  12 . 

24.4 

*0.0 

35.4 

0.0 

11.4 

7.2 

Jan.  17  19 . 

28.0 

22.6 

30.0 

0  0 

11  4 

Jan.  25  27 . 

33.2 

16.6 

29.4 

0.0 

9.4 

Feb.  1  3 . 

25.4 

28.6 

34.2 

0.0 

10.2 

Feb.  8  10 . 

24.0 

16.8 

19.6 

0.0 

8.4 

Feb.  14  16 . 

32.0 

22.6 

21.6 

0.0 

0.0 

Feb.  22  24 . 

21.4 

17.2 

32.8 

0.0 

0  0 

Mar.  5  7 . 

24.0 

26.4 

25.4 

0  0 

0  0 

Mar.  13  15 . 

18.6 

28.4 

20.8 

0.0 

11.6 

Mar.  20  22 . 

25.0 

25.8 

27.0 

0.0 

11.2 

‘The  first  day  of  fasting  began  at  2  p.  m.,  the  last  feed  having  been  given  between  7  and  8 
a.  m.  of  that  day.  The  water  was  drunk  at  2  p.  m.t  at  the  beginning  of  each  day. 

J  Steer  fasted  for  standard  metabolism  experiment,  but  experiment  was  not  made. 


of  water  will  be  needed  when  animals  are  on  full  ration.  In  the  study  of 
undernutrition  in  steers  it  was  found  that  more  nearly  2.5  or  3  kg.  of  water 
were  consumed  per  kilogram  of  dry  matter  in  feed,  when  the  animals  were 
on  a  submaintenance  ration  consisting  exclusively  of  hay.c  When  no  food 
is  given  to  these  large  ruminants,  it  is  not  impossible  to  conceive  that  no 
water  would  be  necessary  and  that,  since  the  disintegration  of  flesh  would 
give  enough  water  to  carry  off  the  waste  products,  the  animals  wrould  act 
much  like  dogs,  which  withstand  the  complete  withdrawal  of  food  and  water 


°  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  203,  1915,  p.  84. 

6  Kellner,  Die  Ernahrung  der  landwirtschaftlichen  Nutztiere,  9th  ed.,  Berlin,  1920,  p.  185. 
e  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  114. 


DRINKING-WATER 


77 


for  long  periods.  In  view  of  the  uncertainty  as  to  the  water  needs  of  fasting 
steers,  however,  it  seemed  best  not  to  attempt  to  control  the  amount  of 
water  consumed,  or,  indeed,  to  withhold  water  entirely,  but  to  permit  the 
animals  to  drink  voluntarily  each  day. 

The  irregularity  in  the  water  consumption  of  animals,  particularly  during 
fasting,  made  it  desirable  to  secure  weights  of  the  water  actually  consumed. 
For  this  reason  the  animal  was  weighed  immediately  before  and  after  drink¬ 
ing  and  the  tub  of  water  was  likewise  weighed.  The  time  of  drinking  and 
the  temperature  of  the  water  were  both  recorded,  as  it  is  now  being  recog¬ 
nized  more  clearly  that  the  introduction  of  very  cold  water,  particularly  in 
large  quantities,  into  an  animal’s  alimentary  tract  makes  heavy  demands 
upon  its  store  of  heat  and  undoubtedly  profoundly  inhibits  the  activity  of 
the  alimentary  tract.  In  most  of  these  fasts  precautions  were  taken  to  have 
the  temperature  of  the  water  not  far  from  15°  to  20°  C.,  for  in  much  of 
our  previous  work  on  submaintenance  feeding  the  water  was  extremely 
cold,  at  times  being  but  1  or  2  degrees  above  0°  C.° 

In  studying  fasting  conditions  it  would  be  advantageous  to  know  exactly 
the  salt-content  of  the  drinking-water.  This  was  not  determined.  The 
water  used  was  obtained  from  the  university  water  system,  supplied  by  a 
deep  well.  It  was  frequently  analyzed  and  found  to  be  of  a  high  degree  of 
purity.  Theoretically,  of  course,  it  would  have  been  better  to  have  given 
the  animals  only  distilled  water,  as  was  done  in  the  long  study  of  the  fasting 
man  made  by  the  Nutrition  Laboratory.* 6 

Records  of  the  water  consumed  by  the  steers  prior  to  and  during  the 
series  of  2-day  fasts  in  1923  are  given  in  Table  18  and  similar  records  for 
the  longer  fasts  are  given  in  Table  19. 

The  picture  of  the  water  consumption  on  the  three  days  with  feed  prior 
to  the  short  fasts  in  1923  gives  a  reasonably  close  indication  of  the  normal 
water  consumption  of  these  animals  when  living  at  an  essentially  uniform 
nutritive  plane,  upon  a  constant  ration.  Thus,  during  the  feeding-periods 
from  January  to  April  1923  the  animals  received  daily  9  kg.  of  hay  and  2 
kg.  of  a  meal  mixture  made  up  of  equal  parts,  by  weight,  of  corn  meal, 
linseed  meal,  and  wheat  bran.  On  this  feed  the  consumption  of  water  was 
usually  reasonably  constant,  amounting  to  not  far  from  20  to  25  kg.  per 
day.  There  is  a  marked  exception  in  the  case  of  steer  D  on  the  second  day 
before  the  fast  of  January  9  to  12,  1923.  On  this  day  the  afternoon  ration 
of  hay  and  meal  had  been  withheld,  as  it  was  planned  to  carry  out  an 
experiment  in  the  respiration  chamber  the  next  morning.  No  experiment 
was  made,  however.  At  2  p.  m.  on  this  day  steer  D  consumed  no  water.  A 
possible  explanation  for  this  will  be  given  later  (see  p.  79). 

Prior  to  the  longer  fasts  of  5  to  14  days,  the  animals  were  on  varying 
nutritive  planes  and  hence  drank  varying  amounts  of  water  and  consumed 
varying  amounts  of  feed  before  the  fasts.  This  fact  must  be  taken  into 
consideration  in  interpreting  the  records  for  water  consumption  in  the  longer 
fasts  reported  in  Table  19.  During  the  three  days  with  feed  prior  to  the 
first  four  fasts  the  daily  water  consumption  was  usually  not  far  from  30  to 

°  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  112. 

6  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  203,  1915,  p.  85. 


78 


METABOLISM  OF  THE  FASTING  STEER 


1  The  values  given  in  this  table  represent  the  water  drunk  at  the  beginning  of  the  day. 


DRINKING-WATER 


79 


35  kg.,  varying  somewhat  with  the  animal,  the  records  for  both  steer  C  and 
steer  D  prior  to  the  first  experiment  in  December  1921  being  somewhat 
lower  than  any  of  the  others.  The  ration  prior  to  these  fasts  was  an  essen¬ 
tially  maintenance  ration  of  hay  and  meal.  Particular  attention  should 
be  paid  to  the  records  of  water  consumption  preceding  the  two  fasting 
experiments  in  March  1924,  with  steers  C  and  D,  and  the  two  experiments 
in  February  1924,  with  steers  E  and  F.  In  these  instances  all  four  animals 
were  on  a  distinctly  submaintenance  plane  of  nutrition  and  had  been  con¬ 
suming  regularly  less  water  than  they  had  under  normal  conditions. 

During  the  first  day  of  fasting  the  intestinal  tract  of  the  steer,  which  has 
been  receiving  maintenance  rations,  may  still  contain  a  large  amount  of 
feed,  which  has  not  been  entirely  digested  or  absorbed,  and  which  needs 
water  for  its  further  hydration.  The  amount  of  water  consumed  on  the 
first  day  of  fasting  is  therefore  of  unusual  interest. 

From  Table  18  it  will  be  seen  that  in  every  instance  the  animals  drank 
no  water  at  the  beginning  of  the  first  fasting  day,  although  they  were  offered 
water  and  had  actually  been  without  feed  only  for  6  hours.  At  the  begin¬ 
ning  of  the  second  day  of  the  fast,  or  the  end  of  the  first  day,  when  no  feed 
had  been  eaten  for  about  30  hours,  steer  C  drank  water  on  every  occasion 
and  steer  D  on  all  but  three  occasions.  Indeed,  the  amount  of  water  taken 
was  reasonably  uniform  at  about  9  or  10  kg.  In  the  one  experiment  with 
both  animals  which  lasted  for  3  days  the  amount  of  water  consumed 
decreased  on  the  third  day  to  6  and  7  kg.,  respectively. 

In  the  longer  fasts,  in  contradistinction  to  the  short  fasts,  the  animals 
drank  water  in  all  but  three  instances  at  the  beginning  of  the  first  day  of 
fasting,  but  there  are  numerous  instances  when  no  water  was  consumed  at 
the  beginning  of  the  second  day  of  fasting.  The  data  for  water  consump¬ 
tion  during  the  4-day  experiments  with  steers  E  and  F  in  1924  and  1925 
also  show  that  the  animal  drank  water  at  the  beginning  of  the  first  day  of 
fasting,  but  sometimes  did  not  drink  at  the  beginning  of  the  second  day. 
This  difference  in  the  picture  presented  by  the  short  fasts  and  that  presented 
by  the  longer  fasts  and  the  fasts  in  1924  and  1925  is  probably  due  to  several 
factors.  Thus,  the  difference  in  environmental  temperature  may  have  been 
one  cause  of  the  difference  in  water  consumption.  The  longer  fasts  were 
made  at  relatively  high  environmental  temperatures,  and  no  attempt  was 
made  to  alter  the  temperature  during  the  fast.  In  the  short  fasts,  on  the 
contrary,  the  effect  of  both  high  and  low  environmental  temperatures  was 
studied,  the  animal  being  occasionally  subjected  to  a  low  temperature  on 
one  day  and  to  a  much  higher  temperature  on  the  very  next  day,  or  vice 
versa.  During  the  period  of  2-day  fasts,  moreover,  there  were  such  short 
intervals  of  feeding  between  the  fasts  that  the  animals  probably  did  not 
have  time  to  recuperate  entirely  from  one  fast  before  another  was  started. 
Thus,  the  animals  were  fasted  approximately  once  a  week,  and  there  was 
almost  a  continuous  rhythm  of  temporary  digestive  disturbance,  due  to  the 
fasting,  with  irregularity  of  water  intake  following  the  fast.  On  the  first 
day  or  so  after  the  fast  the  water  consumption  was  low,  but  there  was  a 
tendency  to  make  up  for  this  in  the  subsequent  days  and  a  high  water  con¬ 
sumption  was  reached  after  4  or  5  days.  The  animal  was  then  apt  to  refuse 


80 


METABOLISM  OF  THE  FASTING  STEER 


water  for  a  day.  By  pure  coincidence,  so  far  as  is  known,  this  seeming 
rhythm  in  water  consumption  due  to  the  intermittent  fasting  happened  to 
correspond  with  the  fasting  schedule. 

The  records  for  the  water  consumption  in  the  experiments  made  in  1924 
and  1925  were  for  steers  E  and  F,  whereas  the  records  for  the  earlier  fasts 
were  chiefly  with  steers  C  and  D.  In  these  later  experiments  steers  E  and 
F  were  kept  for  4  days  continuously  inside  the  respiration  chamber.  The 
experimental  conditions  were  therefore  distinctly  different  from  the  stall 
conditions  obtaining  in  the  series  of  long  and  short  fasts,  in  that  the  animal 
when  inside  the  respiration  chamber  is  in  an  atmosphere  of  much  higher 
humidity,  necessitated  by  the  lower  ventilation,  than  he  is  when  outside  the 
chamber  in  his  stall.  Consequently  the  data  for  drinking-water  obtained 
in  the  later  experiments  are  not  strictly  comparable  with  those  obtained  in 
the  long  and  short  fasts.  It  should  be  pointed  out,  however,  that  one  would 
expect  that  the  days  when  the  animal  would  not  drink  would  be  the  days 
when  he  was  inside  the  chamber,  when  the  humidity  was  high,  and  the 
experiments  in  1924  and  1925  show  that  this  was  not  the  case,  thus  sug¬ 
gesting  that  the  humidity  had  but  little  effect  on  the  loss  of  moisture  from 
the  lungs  and  skin. 

The  data  for  the  water  consumption  during  the  progress  of  the  fast  indi¬ 
cate  that  at  the  beginning  of  the  second  day  no  water  was  consumed  in  ten 
instances,  although  as  much  as  10  to  13  kg.  were  taken  in  three  instances. 
On  the  third  day  there  was  a  disposition  to  a  return  to  water  consumption. 
On  the  fourth  day  steer  C  drank  no  water  except  in  the  fast  in  December 
1921,  when  he  took  0.4  kg.  With  steer  D,  however,  the  water  consumption 
on  the  fourth  day  of  fasting  varied  from  0.0  to  as  high  as  16.8  kg.  On 
the  fifth  day  irregularity  in  the  different  experiments  is  again  shown,  large 
amounts  being  sometimes  taken  by  steer  D.  On  the  sixth  day  and  the 
following  days  the  water  intake  is  irregular. 

No  long  periods  of  complete  refusal  of  water  are  noted,  save  in  the  experi¬ 
ment  with  steer  C  after  pasture  in  November  1923,  when  for  4  days  he 
drank  no  water,  and  in  the  experiment  in  March  1924,  after  submaintenance 
feeding,  when  steer  C  drank  practically  no  water  for  10  days,  if  one  excepts 
the  0.2  kg.  taken  on  the  seventh  day  and  the  1.4  kg.  taken  on  the  ninth  day. 
Steer  D  drank  no  water  in  the  March  experiment  following  submaintenance 
feeding,  except  on  the  fourth  and  seventh  days,  when  11  kg.  were  taken. 
Steer  E,  which  fasted  after  submaintenance  feeding,  drank  small  amounts 
of  water  during  the  entire  fast,  and  steer  F,  also  fasting  on  a  low  nutritive 
plane,  drank  no  water  at  all  for  three  days. 

In  general,  distinctly  less  water  was  consumed  by  both  steer  C  and  steer 
D  when  fasting  after  submaintenance  feeding  or  after  pasture  than  when 
fasting  on  a  higher  nutritive  plane.  Probably  the  large  amount  of  water  in 
the  succulent  grass,  or  perhaps  the  possibility  that  the  steers  had  been  drink¬ 
ing  just  prior  to  leaving  pasture,  may  have  contributed  a  plentiful  amount 
of  water  to  the  animal’s  organism  at  the  time  of  the  fasts  off  pasture.  One 
may  conclude,  therefore,  that  when  steers  are  liberally  supplied  with  water, 
as  on  pasture  feeding,  the  extra  water  demands  of  the  body  are  relatively 
small  and  for  several  days  little  or  no  water  may  be  taken.  Similarly,  when 


FECES 


81 


the  animals  are  on  a  low  nutritive  plane  and  receiving  a  small  ration  of 
hay,  there  may  be  a  long  period  of  time  when  no  water  or  very  little  water 
is  taken.  The  inference  is  that  drinking-water  might  be  withheld  from 
steers  during  a  fast,  especially  under  conditions  of  submaintenance  feeding 
and  probably  after  pasturage,  without  detriment  to  the  animal.  The  long 
periods  of  complete  abstinence  from  water  while  fasting,  noted  especially 
with  steer  C,  are  strikingly  similar  to  experiences  in  fasting  experiments 
made  with  dogs.  In  such  cases  the  fasting  steer  is  practically  a  carnivorous 
animal,  subsisting  upon  its  own  flesh  and  not  requiring  any  appreciable 
amount  of  water  to  maintain  its  water-balance,  for  little  or  no  water  was 
taken  during  the  later  stages  of  fasting,  although  water  was  offered  every 
day. 

In  connection  with  the  feeding  of  these  steers,  certain  definite  observa¬ 
tions  regarding  the  consumption  of  water  can  be  recorded.  When  the  steers 
were  fed  both  morning  and  evening  and  were  offered  water  at  2  p.  m.,  that 
is,  between  the  two  meal  times,  they  usually  drank.  If  the  afternoon  feed 
and  the  following  morning’s  feed  were  withheld,  they  usually  did  not  drink 
at  2  p.  m.  the  next  day.  In  those  few  instances  when  they  did  drink  after 
both  feeds  had  been  withheld,  a  large  volume  of  urine  was  excreted  during 
the  next  24  hours.  This  observation  belongs,  more  strictly  speaking,  in  the 
section  discussing  the  volume  of  urine,  but  is  introduced  here  simply  to 
show  the  immediate  effect  of  water  consumption  upon  the  output  of  urine 
when  the  daily  ration  is  withheld  and  there  is  not  a  corresponding  supply  of 
dry  matter  of  feed  to  absorb  the  water. 

In  none  of  these  fasting  experiments  was  salt  given.  The  animals  had 
to  rely  solely  upon  the  salt  normally  present  in  the  drinking-water,  an 
analysis  of  which  shows  that  they  received  a  very  small  amount  of  mineral 
matter  from  this  source. 

A  general  inspection  of  the  detailed  records  secured  during  this  research 
shows  that  when  the  steers  are  fed  hay  and  meal,  the  amount  of  water  con¬ 
sumed  bears  a  fairly  close  relationship  to  the  total  intake  of  dry  matter  in 
the  ration. 

FECES 

The  differences  in  the  amounts  of  feces  excreted  by  the  dog,  by  man,  and 
by  the  ruminant  are  in  large  part  explained  by  the  nature  of  their  intestinal 
tracts  and  particularly  by  the  nature  of  their  food.  The  residue  or  fill  in 
the  intestinal  tract  of  the  ruminant  is  very  large,  amounting  at  times  to 
over  20  per  cent0  of  the  animal’s  weight,  whereas  the  intestinal  residue  in 
the  case  of  man  or  the  dog  is  small.  Fasting  dogs  frequently  pass  no  feces 
for  a  long  period.  Indeed,  the  man  who  fasted  at  the  Nutrition  Laboratory 
for  31  days  passed  no  feces  during  the  entire  time.6  The  large  intestinal 
content  or  ballast  of  the  steer,  however,  although  for  some  little  time  sub¬ 
ject  to  digestive  processes  and  to  fermentations,  must  be  expelled,  because 
a  large  part  of  it  is  not  digested  by  the  animal  organism.  A  study  of  the 
feces  of  these  fasting  steers  was  therefore  made  for  the  purpose  of  securing 

°  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  pp.  107  and  108. 

k  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  203,  1915,  p.  230. 


82 


METABOLISM  OF  THE  FASTING  STEER 


information  on  several  points:  first,  regarding  the  actual  mass  of  feces 
passed,  particularly  with  reference  to  the  length  of  the  fast;  second,  regard¬ 
ing  the  effect  of  the  previous  ration  upon  this  mass;  and  third,  regarding 
the  chemical  composition  of  the  feces  as  influenced  both  by  fasting  and  by 
the  previous  ration. 

Amount  and  Frequency  of  Defecations 

Earlier  experience  with  steers  during  undemutrition  showed  that  exten¬ 
sive  changes  in  the  physical  appearance  of  feces  were  not  accompanied  by 
great  alterations  in  the  moisture-content.  It  is  deemed  permissible,  there¬ 
fore,  to  discuss  the  fecal  excretion  of  these  fasting  steers  on  the  basis  of  the 
fresh  weight  and  to  defer  for  the  moment  a  consideration  of  the  amount  of 
dry  matter,  which  involves  a  knowledge  of  the  water-content. 

Due  to  the  irregularity  in  the  expulsion  of  feces  by  all  cattle,  the  indi¬ 
vidual  defecations  should  be  weighed  separately.  To  have  an  attendant 
constantly  at  hand  to  collect  the  feces,  as  dropped,  is  perhaps  the  simplest 
method,  but  it  is  expensive.  Many  experimenters  have  had  recourse  to 
various  types  of  ducts,  either  of  rubber  or  oiled  silk,  to  conduct  the  feces, 
as  passed,  into  reasonably  air-tight  containers.  The  small  number  on  our 
experimental  staff  would  not  permit  the  first  of  these  methods  of  collection, 
and  the  second  method  would  not  have  much  advantage  over  the  simple 
form  of  trap  shown  in  a  previous  report,0  through  which  the  feces  drop 
directly  into  convenient  receptacles  below.  When  the  animals  are  fairly 
well  fed  this  latter  method  is  ideally  simple  and  is  probably  subject  to  no 
great  error,  for  the  losses  from  vaporization  are  relatively  small  in  propor¬ 
tion  to  the  total  weight  of  feces.  On  the  other  hand,  in  the  weighing  of  the 
very  small  amounts  of  feces  occurring  during  undernutrition,  and  particu¬ 
larly  during  fasting,  the  error  may  be  relatively  larger.  Any  losses  in  weight 
would,  however,  undoubtedly  be  in  large  part  due  simply  to  vaporization 
of  water,  although  a  loss  of  ammonia  may  take  place  even  if  the  feces  stand 
in  a  can  for  only  a  few  hours. 

The  weight  of  fresh  feces  voided  each  day  during  the  fasts  of  5  to  14  days 
and  the  average  daily  weight  of  feces  for  a  week  with  feed  preceding  each 
of  these  fasts  have  been  tabulated  in  Table  20.  These  daily  weights,  how¬ 
ever,  do  not  represent  exact  24-hour  separations.  The  steers  did  not  volun¬ 
tarily  defecate  exactly  at  a  given  moment.  The  feces  cans  were  removed 
each  day  at  2  p.  m.,  but  feces  might  have  been  passed  either  immediately 
before  2  p.  m.  or  several  hours  before,  and  the  actual  time  between  the  first 
and  last  defecation  on  any  given  date  may  be  longer  or  shorter  than  24 
hours.  It  was  possible,  therefore,  only  to  approximate  the  true  daily  excre¬ 
tion  by  making  the  collections  in  24-hour  periods,  and  it  seems  inadvisable 
to  attempt  to  compute  the  hourly  rate. 

As  pointed  out  in  an  earlier  report,6  the  fecal  excretion  is  notably  affected 
by  the  character  and  the  amount  of  the  ration.  The  most  pronounced  factor 
affecting  the  character  and  the  amount  of  feces  is  clearly  the  bulk  of  fibrous 
material,  hay,  rather  than  the  amount  of  meal,  although  it  is  common 

“Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  31. 

b  Ibid.,  pp.  121  et  seq. 


Table  20. — Daily  excretion  of  fresh  feces  before  and  during  fasts  of  5  to  H  days 


FECES 


1  This  value  represents  a  period  of  collection  of  only  17  hours,  from  2  p.  m.,  Mar.  3,  to  7  a.  m.t  Mar. 


84 


METABOLISM  OF  THE  FASTING  STEER 


experience  that  the  feeding  of  meal  in  large  amounts,  particularly  oil  meal, 
has  a  tendency  to  scour  animals  and  results  in  more  watery  and  voluminous 
feces. 

An  examination  of  the  data  obtained  during  the  feeding-periods  shows 
that  in  general  the  weight  of  fresh  feces  is  twice  that  of  the  ration.  Thus, 
during  the  periods  of  feeding  in  1921  and  1922,  when  about  9  kg.  of  hay 
and  from  2  to  6  kg.  of  meal  were  consumed  daily,  24  kg.  of  feces  were  passed 
daily  on  the  average  both  by  steer  C  and  by  steer  D.  From  January  to 
April  1923  these  steers  also  received  a  maintenance  ration  of  hay  and  meal, 
but  the  food  intake  was  disturbed  by  the  numerous  short  periods  of  fasting 
and  the  average  weight  of  feces  passed  daily  during  the  feeding  periods  was 
therefore  somewhat  smaller  than  in  the  earlier  maintenance  periods.  The 
marked  reduction  in  ration  prior  to  the  fast  in  March  1924  was  instantly 
reflected  in  a  pronouncedly  lower  fecal  expulsion.  Thus,  steers  C  and  D 
had  been  receiving  daily  only  4.5  kg.  of  hay  and  no  meal,  and  as  a  result 
the  average  daily  amount  of  feces  was  only  about  7  kg.,  i.  e.,  still  nearly 
twice  as  great  as  the  ration.  A  similar  picture  is  noted  with  steers  E  and 
F  on  a  submaintenance  ration  of  2.5  kg.  of  hay  and  100  gm.  of  meal  in 
February  1924,  when  their  daily  fecal  excretion  averaged  about  4.5  kg.  It 
is  especially  worthy  of  note  that  both  the  younger  and  the  older  animals, 
considered  as  duplicates  or  pairs,  showed  much  the  same  reaction  to  the 
ration,  as  exemplified  by  the  amount  of  feces  excreted. 

There  is  a  tendency  for  the  daily  fecal  excretion  of  steer  D  to  be  slightly 
smaller  than  that  of  steer  C.  Indeed,  detailed  records  for  almost  every 
day  from  November  26,  1921,  through  January  5,  1923,  show  that  on  the 
average  steer  D  excreted  14.81  kg.  of  feces  per  day  and  steer  C  15.42  kg., 
although  both  animals  received  the  same  treatment,  side  by  side  in  the 
same  stalls,  were  subjected  to  the  same  number  of  respiration  experiments, 
consumed  the  same  amount  of  food,  and  drank  the  same  amount  of  water 
(21.7  kg.,  steer  C;  21.5  kg.,  steer  D). 

In  the  case  of  all  four  steers,  the  collection  of  feces  for  the  first  day  of 
fasting  began  at  2  p.  m.,  at  which  time  the  feces  containers  were  replaced 
with  empty  containers.  The  last  feed  prior  to  the  fast  was  given  in  the 
morning  between  6  and  8  o’clock.  Hence  the  weights  of  feces  reported  for 
the  first  day  of  fasting  represent  a  24-hour  period  beginning  about  6  or  8 
hours  after  the  last  feed.  The  weights  of  feces  reported  for  the  first  day 
of  the  March  1924  fast,  however,  represent  only  a  17-hour  period  from 
2  p.  m.  to  7  a.  m.,  as  it  was  decided  on  the  second  day  to  have  the  24-hour 
periods  begin  at  7  a.  m.  instead  of  at  2  p.  m.  In  the  two  November  fasts 
following  pasture  it  was  not  easy  to  determine  exactly  when  the  animals 
had  last  eaten.  The  weights  of  feces  reported  for  the  first  day  of  the 
November  1922  fast  represent  a  period  beginning  6  hours  after  the  steers 
were  brought  in  from  pasture.  In  the  November  1923  fast  the  collection  of 
feces  did  not  begin  until  22  hours  after  the  steers  had  been  brought  in  from 
pasture,  and  the  first  24-hour  collection  of  feces  during  this  fast  is  therefore 
attributed  to  the  second  day. 

On  the  first  day  of  fasting  there  was  a  decrease  in  the  amount  of  feces 
passed,  although  in  most  instances  this  decrease  was  not  pronounced.  In 


FECES 


85 


the  special  series  of  2-day  fasts  during  January,  February,  and  March  1923, 
the  data  secured  regarding  the  excretion  of  feces  support  this  view.  In  this 
series,  in  which  all  the  fasts  followed  maintenance  feeding,  approximately 
19  kg.  of  feces  were  passed  daily  on  the  average  during  the  week  prior  to 
the  fast.  On  the  first  day  of  fasting  there  was  a  general  average  decrease 
to  16  kg.,  or  a  fall  of  16  per  cent.  On  the  second  day  of  fasting  the  average 
expulsion  amounted  to  6  kg.  The  total  average  amount  for  the  first  two 
days  of  fasting  is  therefore  about  22  kg.  or  essentially  that  passed  daily 
during  the  feeding-period.  This  finding,  that  the  total  amount  of  feces 
passed  during  the  first  two  days  of  fasting  is  approximately  equal  to  the 
amount  passed  daily  during  the  feeding-period  preceding  it,  is  also  true  in 
the  case  of  the  longer  fasts  reported  in  Table  20,  both  those  following  main¬ 
tenance  feeding  and  those  following  submaintenance  feeding.  In  the  case 
of  the  fasts  following  pasture,  obviously  no  records  for  the  feeding-period 
were  available. 

The  first  four  long  fasts  of  steers  C  and  D  are  comparable,  because  they 
followed  an  essentially  maintenance  ration.  The  fecal  excretion  on  the  first 
and  second  days  of  these  fasts  is  larger  than  the  excretion  noted  in  the  short 
fasts  in  1923.  Thus,  both  steers  excreted  approximately  24  kg.  during  the 
week  on  feed  before  the  fasts  and  on  the  average  not  far  from  20  kg.  of 
feces  on  the  first  day  of  these  four  fasts.  The  average  percentage  decrease 
on  the  first  day,  however,  is  practically  the  same  as  was  noted  in  the  1923 
series,  i.  e.,  17  per  cent.  This  relatively  small  average  decrease  of  4  kg.  is 
perhaps  surprising,  but  one  should  recall  that  feed  was  actually  eaten  8 
hours  prior  to  the  collection  of  feces  for  the  first  fasting  day.  This  fact, 
coupled  with  the  large  ballast  in  the  intestinal  tract,  minimizes  any  immedi¬ 
ate  effect  of  fasting  upon  the  fecal  discharge. 

In  general,  the  larger  amounts  of  feces  prior  to  these  four  fasts  are  fol¬ 
lowed  by  larger  amounts  of  feces  on  the  first  fasting  day.  In  the  April  fast 
of  steer  C  and  the  June  fast  of  steers  C  and  D,  decreases  in  fecal  excretion 
of  from  4  to  8  kg.  were  noted  on  the  first  day,  but  in  the  other  fasts  the 
decrease  is  more  nearly  2  or  3  kg.  With  the  large  bulk  of  fecal  matter  in 
the  intestinal  tract  and  the  irregularity  of  defecation,  it  is  perhaps  not  sur¬ 
prising  that  the  fecal  output  on  the  first  day  is  not  more  uniform.  The 
length  of  time  intervening  between  the  last  ingestion  of  feed  and  the  begin¬ 
ning  of  the  first  day  of  fasting  and  the  amount  of  the  last  ration  received 
prior  to  the  fast  should  also  be  considered  in  this  connection.  Thus,  some¬ 
what  larger  amounts  of  meal  were  eaten  prior  to  the  fasts  in  January, 
April,  and  June  1922  than  were  eaten  prior  to  the  fast  in  December  1921, 
and  in  all  but  one  instance  the  fecal  excretion  in  these  experiments  is  larger 
than  that  noted  in  the  December  experiment.  The  large  amount  of  meal 
eaten  prior  to  the  fast  in  January  1922  did  not  have  a  pronounced  effect 
upon  the  fecal  excretion  either  before  the  fast  or  on  the  first  day  of  fasting 
in  the  case  of  steer  D,  but  in  the  case  of  steer  C  the  amounts  of  feces 
are  somewhat  larger  than  in  the  1921  experiment,  when  less  meal  was 
eaten.  Before  the  fast  in  June  1922,  when  both  steers  had  been  receiving 
about  8.5  kg.  of  hay  and  4  kg.  of  meal  daily,  there  was  a  distinct  increase 
in  the  average  fecal  output  on  feed  and  the  largest  amounts  of  feces  on  the 
first  day  were  noted  in  this  fast. 


86 


METABOLISM  OF  THE  FASTING  STEER 


After  pasture  the  feces  are  much  smaller  in  amount.  In  the  fast  in 
November  1922  both  steers  voided  only  13.5  kg.  on  the  first  day.  In  the 
fast  in  November  1923  the  feces  were  not  collected  until  the  second  day, 
but  the  average  amount  on  the  second  day,  16.7  kg.,  is  actually  greater  than 
that  observed  on  the  first  day  and  about  three  times  as  great  as  that 
recorded  on  the  second  day  of  the  1922  fast  following  pasture.  Irregularity 
in  pasture  feeding  makes  sharp  conclusions  impracticable. 

In  the  fasts  following  undernutrition  in  1924  the  decrease  in  feces  on  the 
first  day  is  small  with  all  four  animals,  but  likewise  the  initial  amounts  on 
feed  are  small.  The  fecal  discharge  on  the  first  day  of  fasting  is,  however, 
very  small  when  compared  with  the  amounts  voided  in  the  other  fasts 
following  maintenance  rations  or  pasture  feeding. 

Inspection  of  the  data  for  feces  on  feed  and  on  the  first  two  days  of 
fasting  shows  in  general,  therefore,  that  the  decrease  in  feces  on  the  first 
day  of  fasting  is  small  following  maintenance  feeding.  After  submain¬ 
tenance  feeding  the  decrease  is  small  and  the  total  amount  involved  is  like¬ 
wise  small.  In  the  case  of  steers  E  and  F  the  total  amount  on  the  first  day 
is  small,  both  because  the  fasting  followed  submaintenance  feeding  and 
because  the  animals  were  small. 

Because  of  the  continually  decreasing  ballast  and  the  extensive  changes 
in  the  amount  of  water  intake  during  fasting,  great  differences  in  the  fre¬ 
quency  of  defecation,  the  amount  of  each  defecation,  and  the  total  amount 
per  day  are  to  be  expected.  Only  the  total  amount  per  day  is  considered 
in  Table  20.  Records  were  kept,  however,  of  the  amount  and  time  of  each 
defecation  during  all  of  the  fasts  reported  in  Table  20,  except  that  in 
December  1921.  These  records  show  that  in  the  fasts  following  maintenance 
feeding  the  number  of  defecations  on  the  first  day  was  fairly  large,  varying 
from  9  to  12  defecations  during  the  day.  In  the  two  November  fasts  after 
pasture  the  defecations  on  the  first  day  decreased  to  5  or  6  in  number.  In 
the  fasts  following  submaintenance  rations  steers  C  and  D  voided  feces  at 
five  or  six  different  times  during  the  first  day  and  steer  E  at  four  different 
times.  On  the  other  hand,  with  steer  F  there  were  nine  defecations,  all 
reasonably  uniform  in  size.  Aside  from  this  one  instance,  however,  the 
number  of  defecations  on  the  first  day  of  fasting  was  less  following  pasture 
or  submaintenance  feeding  than  following  maintenance  feeding  with  hay  or 
with  hay  and  meal. 

The  frequency  of  defecation  and  the  actual  amount  of  each  defecation  is 
best  shown  graphically.  Accordingly,  the  data  for  the  individual  defeca¬ 
tions  have  been  plotted  for  three  typical  fasts  of  steers  C  and  D,  namely, 
the  14-day  fast  in  April  1922,  the  9-day  fast  after  pasture  in  November 
1922,  and  the  10-day  fast  after  submaintenance  feeding  in  March  1924. 
(See  Fig.  4.)  The  total  daily  excretions  are  recorded  upon  the  chart  in  the 
top  row  of  figures  above  each  curve,  thus  duplicating  the  data  in  Table  20 
for  these  three  fasts. 

In  the  14-day  fast  in  April,  which  followed  maintenance  feeding  of  9  kg. 
of  hay  and  3  kg.  of  meal  daily,  the  number  of  defecations  and  the  amount 
of  each  defecation  were  large  with  both  animals  on  the  first  day.  On  the 
second  day  there  are  fewer  defecations  and  the  total  mass  is  much  smaller. 


FECES 


87 


The  charted  data  for  this  fast  show  a  distinctly  downward  trend  both  in  the 
number  of  defecations  and  the  amount  of  each  defecation  until  about  the 
seventh  day.  After  the  seventh  day  there  are  a  large  number  of  small 
defecations  daily.  This  is  particularly  true  of  steer  D,  whose  total  daily 
fecal  discharge  on  the  average  is  actually  not  quite  so  large  as  is  that  of 
steer  C.  On  the  last  day  of  the  fast,  for  example,  steer  D  had  11  defecations, 
practically  all  under  100  grams  each. 


6m 


Fig.  4. — Individual  defecations  of  steers  C  and  D  during  fasts  in  April  and  November  1922,  and 

March  1924 

The  two  curves  at  the  bottom  of  the  chart  represent  the  fast3  in  April  1922,  which  followed  a 
maintenance  ration  of  9  kg.  of  hay  and  3  kg.  of  meal.  The  two  curves  in  the  middle  are  for 
the  November  fasts,  which  followed  pasture  feeding.  The  two  curves  at  the  top  are  for  the 
March  fasts,  which  followed  a  submaintenance  ration  of  4.5  kg.  of  hay.  The  figures  in  the 
top  row  against  each  curve  represent  the  total  daily  weights  of  fresh  feces  in  kilograms,  those 
in  the  middle  row  the  kilograms  of  dry  matter  in  feces  per  day,  and  those  in  the  bottom 
row  the  grams  of  fecal  nitrogen  per  day. 

A  relationship  between  the  amount  of  water  consumed  per  day  and  the 
consistency  and  the  amount  of  feces  passed  has  been  observed  frequently, 
both  in  our  series  of  undemutrition  and  of  fasting  experiments.  It  is  not 
unlikely  that  some  of  the  irregularities  shown  in  Fig.  4  are  due  to  differences 
in  water  intake.  In  no  instance,  however,  is  a  striking  effect  of  the  water 
consumption  upon  the  mass  of  feces  indicated  on  any  given  day.  Reference 
to  the  data  for  water  consumption  (see  Table  19,  p.  78)  shows,  for  example, 
that  on  the  eleventh  day  of  this  April  fast  steer  C  passed  a  relatively  large 
amount  of  feces,  2.6  kg.,  and  drank  5.2  kg.  of  water.  Steer  D,  on  the  other 
hand,  drank  8.4  kg.  of  water  on  the  tenth  day  of  this  fast,  but  there  was 
practically  no  change  in  the  weight  of  fresh  feces. 


88 


METABOLISM  OF  THE  FASTING  STEER 


The  daily  excretion  is  usually  somewhat  less  than  half  as  much  on  the 
second  day  as  on  the  first,  save  in  the  March  fast  after  submaintenance 
feeding.  The  total  daily  amount  falls  off  fairly  regularly  thereafter,  but 
from  the  fifth  day  on  the  average  excretion  of  all  animals  is  not  far  from 
1.5  kg.  per  day.  Feces  were  passed  upon  every  day  of  the  fasting  experi¬ 
ments,  with  the  single  exception  of  the  tenth  day  in  the  March  1924  fast  of 
steer  C,  after  submaintenance  feeding.  It  is  clear  that  the  previous  plane 
of  nutrition,  particularly  the  submaintenance  plane,  affects  the  fecal  excre¬ 
tion.  The  influence  of  pasture  feeding  is  noticeable  only  for  about  3  days, 
although  the  amounts  of  feces  excreted  by  both  steers  during  the  fast  in 
November  1923  were  large  even  after  the  third  day,  indeed  larger  than  in 
most  of  the  other  fasts. 

A  quantitative  study  of  either  the  total  daily  amounts  of  feces  or,  indeed, 
the  dry  matter  of  feces,  must  take  into  account  the  fact  that  the  defecations 
of  these  animals  are  involuntary,  the  ballast  is  very  large,  and  considerable 
differences  in  water  intake  occur.  Only  the  most  general  conclusions  regard¬ 
ing  the  amount  and  rate  of  defecations  are,  therefore,  justifiable,  for 
undoubtedly  complications  are  introduced  by  the  water  intake,  the  character 
of  the  feed  (relative  proportion  of  coarse  fiber  and  concentrates),  and  the 
time  elapsing  between  the  last  feeding  and  the  beginning  of  the  collection 
of  feces. 

It  is  perhaps  to  be  regretted  that  no  provision  could  be  made  for  the  sepa¬ 
ration  of  feces,  particularly  by  the  chromic  oxide  method  of  Edin.a  This 
seemed  impracticable,  and  doubtless  the  marker  would  have  been  retained 
throughout  the  entire  fasting  period.  The  use  of  a  foreign  substance  to 
mark  the  feces  in  ruminants  has  always  been  considered  unsatisfactory.  The 
elaborate  study  of  Ewing  and  Smith,* 6  who  used  rubber  disks  to  indicate  the 
rate  of  passage  of  food  residues  through  the  steer,  showed  that  some  of  the 
rubbers  remained  in  the  animals  for  60  days,  indeed  until  they  were 
slaughtered.  Hence  Ewing  and  Smith  conclude  that  such  a  method  of 
marking  is  unreliable.  The  gross  contents' of  the  alimentary  tract  of  steers 
is  well  illustrated  in  their  report.  Thus,  they  find  that  with  6  steers,  weigh¬ 
ing  on  the  average  380  kg.,  the  gross  contents  of  the  intestinal  tract 
varied  from  36.6  to  70.8  kg.;  5  of  the  6  steers  had  a  residue  of  60  kg.  or 
more.  The  percentage  of  dry  matter  in  these  contents  varied  from  6.07  to 
12.92,  averaging  not  far  from  9  per  cent.  The  authors  conclude  that  the 
time  required  for  the  ordinary  ration  to  pass  through  the  intestinal  tract 
probably  varies  between  72  and  84  hours,  the  rate  of  passage  being  largely 
influenced  by  the  nature  and  the  quantity  of  the  ration,  the  importance  of 
the  two  influencing  factors  being  in  the  order  named. 

The  picture  shown  by  steers  E  and  F  is  in  accord  with  that  of  the  two 
large  animals,  if  one  takes  into  account  the  fact  that  they  are  smaller  and 
that  they  had  been  upon  a  submaintenance  ration.  It  is  singular,  however, 
that  the  daily  weights  of  feces  of  each  of  these  smaller  steers  during  their 
fast  following  submaintenance  feeding  should  be  essentially  the  same  as 
were  noted  with  the  larger  animals  when  fasting  after  a  submaintenance 

a  Edin,  Nordiske  Jordbrugsforskeres  Forenings,  Kongres  i  K0benhavn,  July,  1921,  p.  388. 

6  Ewing  and  Smith,  Journ.  Agric.  Research,  1917,  10,  p.  55. 


Fig.  5. — Feces  voided  by  steer  C  on  the  sixth  day  of  fasting,  November  10,  1923 
The  rule  is  15  inches  (38  cm.)  long 


Fig.  6. — Feces  voided  by  steer  D  on  the  fifth  day  of  fasting,  March  8,  1924 
The  squares  are  in  inches,  or  about  2.5  cm. 


FECES 


89 


ration.  Thus,  although  prior  to  these  fasts  steers  C  and  D  excreted  approxi¬ 
mately  7  kg.  of  feces  per  day  and  steers  E  and  F  only  about  4.5  kg.,  during 
fasting  the  total  24-hour  excretions  after  the  first  day  are  much  more 
nearly  uniform. 

The  data  in  Table  20  and  in  Fig.  4  indicate  clearly  that  fasting  greatly 
reduces  the  fecal  excretion,  which,  however,  continues  throughout  the  entire 
fast,  irrespective  of  its  length.  The  previous  plane  of  nutrition  affects  the 
total  daily  amounts,  and  even  after  pasture  the  fill  and  fecal  excretion  dur¬ 
ing  the  fast  remain  at  a  relatively  high  level.  With  at  least  one  steer  the 
frequency  of  defecation  greatly  increased  toward  the  end  of  the  fast. 

Physical  Characteristics  of  Feces 

In  an  earlier  report®  attention  was  called  to  the  striking  differences  in  the 
characteristics  of  the  feces  when  the  animals  were  upon  submaintenance 
rations  and  when  upon  full  feed.  In  the  latter  instance  the  feces  were  semi¬ 
fluid,  would  not  hold  form,  and  were  very  bulky.  When  the  steers  were 
upon  submaintenance  rations,  their  feces  became  much  harder  and  more 
pilular  in  form,  resembling  in  many  instances  the  feces  of  a  horse.  The 
determinations  of  water  in  these  feces  did  not  show  so  great  a  difference 
in  the  percentage  of  moisture  as  would  be  expected  from  the  striking  differ¬ 
ence  in  physical  appearance.  Indeed,  a  difference  of  only  2  or  3  per  cent 
in  the  water-content  was  noted.  It  seemed  incredible  that  this  small  per¬ 
centage  difference  in  water-content  could  be  accompanied  by  such  a  great 
difference  in  the  physical  configuration  of  the  feces.  In  connection  with  the 
study  of  fasting  steers  opportunity  was  had  to  confirm  this  observation,  for 
steers  C,  D,  E,  and  F  were  at  varying  times  upon  submaintenance  rations. 
During  their  submaintenance  feeding,  similar  changes  in  the  physical  char¬ 
acteristics  of  the  feces  were  noted,  and  the  chemical  analyses,  especially  the 
water  determinations,  show  that  these  great  changes  can  take  place  without 
appreciable  alterations  in  the  water- content. 

Comments  of  the  observers  regarding  the  physical  characteristics  of  the 
feces  during  the  14-day  fast  in  April  1922  are  typical  of  the  physical  char¬ 
acteristics  of  the  feces  in  practically  all  of  the  fasts.  The  feces  at  the  begin¬ 
ning  of  the  fast  in  April  1922  were  soft  and  very  plastic,  as  would  normally 
be  expected  from  a  ration  containing  3  kg.  of  a  meal  mixture  having  a  rela¬ 
tively  large  proportion  of  linseed  meal  and  bran.  As  the  amount  of  feces 
decreased  during  the  progress  of  the  fast,  the  feces  became  visibly  firmer, 
taking  on  a  dry,  pilular  form  by  the  fifth  day.  By  the  eighth  day  the  con¬ 
sistency  of  the  feces  became  more  variable,  some  passages  being  firm  and 
fibrous  in  appearance,  and  others,  especially  those  passed  in  the  respiration 
chamber,  being  soft.  This  latter  condition  was  more  marked  with  steer  C. 
Variability  in  the  physical  consistency  of  the  feces,  especially  in  the  latter 
periods  of  fasting,  is  noted  likewise  in  the  water-content  of  the  feces,  strik¬ 
ingly  high  percentages  of  water  being  found.  (See  Table  21,  p.  90.)  The 
extremely  dry,  pilular  form  which  fasting  feces  may  assume  is  excellently 
illustrated  in  Figs.  5  and  6,  which  show  the  feces  of  steer  C  on  November 
10, 1923,  the  sixth  day  of  the  fast,  and  of  steer  D  on  March  8,  1924,  the  fifth 
day  of  the  fast  following  submaintenance  feeding. 


“Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  125. 


Table  21. — Percentage  of  dry  matter  in  feces  during  fasts  of  5  to  14  days 


90 


METABOLISM  OF  THE  FASTING  STEER 


1  There  were  no  defecations  between  7  a.  m.,  Mar.  12,  and  7  a.  m.,  Mar.  13,  but  0.62  kg.  of  feces  were  passed  in  the  respiration  chamber  between 
7h  10m  and  10h  25m  a.  m.,  Mar.  13,  before  the  steer  was  fed.  The  dry  matter  in  these  feces  was  20.6  p.  ct. 


FECES 


91 


Another  pronounced  characteristic  of  the  feces  during  the  fasting  experi¬ 
ments  was  an  exceedingly  offensive  odor,  which  frequently  was  noticed 
toward  the  end  of  the  fast. 

Chemical  Composition  of  Feces 

The  difficulty  of  avoiding  loss  of  moisture  and  frequently  of  nitrogen 
(ammonia)  in  the  drying  of  feces  made  it  necessary  to  determine  the 
nitrogen-content  directly  in  fresh  feces.  The  water-content  was  determined 
by  subjecting  a  sample  of  approximately  10  gm.  of  fresh  feces  to  the  usual 
process  of  drying.  With  but  few  exceptions  these  two  determinations  were 
made  on  each  day’s  collection  of  feces  during  the  long  fasts  and  on  a  com¬ 
posite  sample  of  the  feces  passed  during  the  entire  fasting-period,  as  well 
as  on  a  composite  sample  of  feces  passed  during  the  feeding-periods  just 
preceding  and  following  the  fasts.  No  correction  was  made  for  loss  of 
material.  Further  analyses  of  the  feces  were  impracticable,  and  the  study 
of  the  chemical  composition  of  fasting  feces  is  confined  solely  to  the 
analyses  of  the  water-content  and  the  nitrogen-content. 

Dry  Matter  in  Feces 

The  marked  changes  in  the  physical  appearance  of  the  feces  made  the 
determinations  of  water-content  especially  interesting,  in  view  of  the  lack 
of  correlation  between  major  changes  in  physical  appearance  and  changes 
in  water-content  previously  noted  in  the  undernutrition  study  with  steers. 
The  percentages  of  dry  matter  in  the  feces,  not  only  for  each  24-hour  col¬ 
lection  of  feces  during  the  fasting-periods,  but  likewise  for  the  composite 
sample  during  the  entire  fast,  are  given  in  Table  21.  Unfortunately,  no 
daily  analyses  were  made  for  the  fasts  in  December  1921,  November  1923, 
and  February  1924.  The  data  for  the  composite  samples  of  feces  during 
the  feeding  periods  preceding  and  following  the  fasts  are  given  in  Table  22. 

From  these  tables  it  can  be  seen  that  in  general  during  the  periods  of 
maintenance  feeding  about  17  to  20  per  cent  of  dry  matter  was  present  in 
the  feces.  During  the  periods  of  submaintenance  feeding  in  February  and 
March  1924  the  percentage  was  not  profoundly  altered.  The  composite 
sample  for  the  first  fast  in  December  1921  likewise  contained  approximately 
19.5  per  cent  of  dry  matter  in  the  case  of  both  steers.  During  the  fasting 
experiments  in  January,  April,  and  June  1922,  there  were  considerable 
variations  in  the  content  of  dry  matter,  with  a  distinct  tendency,  particu¬ 
larly  in  the  14-day  fast,  for  the  percentage  of  dry  matter  to  decrease  after 
the  fourth  to  the  sixth  day.  Up  to  this  time,  however,  the  percentage  of 
dry  matter  is  somewhat  higher  than  during  the  prefasting  feed  period.  In 
the  fasts  in  November  1922  and  March  1924,  on  the  contrary,  the  per¬ 
centage  of  dry  matter  increases  considerably  during  the  fast.  It  is  difficult 
to  account  for  these  differences  in  the  composition  of  the  feces.  The  varia¬ 
tions  in  the  consumption  of  drinking-water  seemingly  explain  the  changes 
occasionally,  but  by  no  means  give  a  satisfactory  explanation  for  this 
anomalous  situation.  The  matter  is  further  complicated  by  reference  to  the 
notes  made  by  the  observers  of  the  physical  consistency  of  the  feces  at  the 
time  of  passage.  (See  p.  89.) 


92 


METABOLISM  OF  THE  FASTING  STEER 


In  the  two  November  fasts  after  pasture  daily  analyses  were  made  only 
for  the  fast  in  1922,  but  a  composite  sample  was  analyzed  for  the  fast  in 
1923.  For  the  fast  following  reduced  rations  in  March  1924,  daily  samples 
were  usually  analyzed.  In  this  fast  and  in  that  in  November  1922  there  is 
a  distinct  tendency  for  the  percentage  of  dry  matter  in  the  feces  of  both 
steers  to  increase  with  the  increasing  length  of  the  fast.  The  picture  of  the 
daily  trend  in  the  fast  in  November  1923  is  not  available,  but  the  one 
analysis  of  the  composite  sample  showed  a  percentage  of  dry  matter  of 
from  19.5  to  20  with  both  animals.  Since,  however,  the  feces  on  the  first 
day  of  the  fast  in  November  19221  had  a  very  low  content  of  dry  matter, 


Table  22. — Percentage  of  dry  matter  in  composite 
samples  of  feces  before  and  after  fasts  of  6  to  14  days 


Feed  periods 

Steer  C 

Steer  D 

Before  fast: 

Nov.  26  to  Dec.  6,  1921. . . . 

18.4 

27.7 

Dec.  22  Jan.  4,1922.... 

19.2 

19.4 

Mar.  31  Apr.  17,  1922.. . . 

19.4 

20.7 

May  9  June  1,1922.... 

17.6 

17.4 

Feb.  26  Mar.  3,1924.... 

23.0 

21.9 

After  fast: 

Dec.  13  to  Dec.  22,  1921 .... 

19.6 

19.8 

Jan.  14  Feb.  2,1922.... 

18.7 

18.4 

Mar.  21  Mar.  31,  1922. . . . 

18.6 

19.3 

May  1  May  9,  1922 .... 

15.8 

18.8 

Mar.  12  Mar.  13,  1924.... 
Mar.  13  Mar.  14,  1924. . . . 

23.7 

18.5 

Steer  E 

Steer  F 

Before  fast: 

Jan.  28  to  Feb.  12,1924.... 

21.9 

21.1 

After  fast: 

Feb.  18  to  Feb.  19,  1924. . . . 

21.5 

18.3 

Feb.  19  Feb.  20,  1924... . 

20.1 

17.6 

16.5  and  16.7  per  cent,  respectively,  and  since  the  first  day’s  defecation  rep¬ 
resents  a  large  part  of  the  total  amount  excreted  during  fasting,  the  low 
values  found  for  the  fast  in  November  1923  are  what  would  be  expected. 
The  percentage  of  dry  matter  on  the  first  day  of  the  November  1922  fast, 
after  the  animals  came  in  from  pasture,  is,  however,  very  low  as  compared 
with  that  of  the  first  day  of  the  March  1924  fast,  prior  to  which  the  animals 
had  been  subsisting  upon  a  submaintenance  ration  of  hay. 

The  difficulties  of  sampling  feces  and  securing  representative  portions  for 
analysis,  the  well-known  loss  during  drying,  and  the  general  difficulty  of 
securing  anhydrous  conditions  in  organic  products  make  determinations  of 
water  in  a  substance  such  as  the  feces  of  ruminants  at  best  somewhat 
uncertain.  The  extraordinarily  high  percentages  of  water  noted  in  Table  21 
in  some  of  the  feces,  especially  toward  the  end  of  the  long  fasts,  has  puzzled 
us  greatly.  Careful  scrutiny  of  the  raw  data,  checking  of  the  computations, 
and  a  comparison  with  the  ocular  observations  of  the  attending  assistants 
confirm  in  large  measure  these  low  percentages  of  water-free  matter.  To 
explain  them  is  not  easy.  It  is  evident  that  the  finding  of  Grouven  that  the 


Table  23. — Daily  weight  of  dry  matter  in  feces  before  and  during  fasts  of  5  to  1 4  days 


FECES 


93 


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94 


METABOLISM  OF  THE  FASTING  STEER 


fill  became  more  watery  as  the  fast  progressed  may  in  part  explain  these 
feces  with  large  percentages  of  water.  Undoubtedly  the  feeding  conditions 
prior  to  the  fasts  affected  somewhat  the  composition  of  the  feces,  especially 
at  the  beginning  of  the  fasts.  In  the  latter  part  of  the  fasts,  at  the  point 
when  about  70  per  cent  of  the  dry  matter  of  fill  has  been  washed  out  through 
the  feces,  the  moisture-content  of  the  feces  seems  to  be  more  rapidly  affected 
by  water  intake  in  quantity  above  the  physiological  daily  needs.  It  is  con¬ 
ceivable  that  in  the  14-day  fasts  the  fill  was  rather  liquid  and  contained  a 
relatively  small  amount  of  dry  matter  of  fibrous  character.  Hence  there 
could  not  be  much  absorption  of  nutritive  material,  and  consequently  there 
was  less  absorption  of  water.  Under  these  conditions  the  addition  of  water 
by  drinking  leaves  the  body  partly  in  the  feces,  as  there  is  less  absorption. 
From  the  data  it  is  clear  that  after  the  first  3  to  5  days  the  amount  of  dry 
matter  defecated  daily  is  more  uniform  than  the  total  amount  of  feces,  the 
greater  variations  corresponding  in  almost  every  instance  to  variations  in 
the  water  intake.  Further  studies  of  the  nature  of  the  fill  and  feces  voided 
during  fasting,  and  particularly  analyses  of  the  fill  in  different  parts  of  the 
alimentary  tract  at  the  end  of  long  fasts,  are  imperative  for  a  thorough 
understanding  of  the  relationship  between  fill,  water-content  of  fill,  and 
excreted  feces,  as  associated  with  the  various  stages  of  prolonged  fasting. 

It  is  perhaps  more  important  to  consider  the  actual  amount  of  dry  matter 
in  feces  as  a  measure  of  the  loss  of  material  to  the  animal  during  the  fasting 
period.  The  weight  of  the  dry  matter  in  feces  per  day  has,  therefore,  been 
recorded  in  Table  23  and  in  Fig.  4.  Except  for  the  fasts  after  submain¬ 
tenance  feeding,  not  far  from  3.5  kg.  of  dry  matter  were  excreted  on  the 
first  day  by  the  two  large  steers.  This  amount  rapidly  decreases  to  about 
1  kg.  on  the  third  day,  and  to  0.5  kg.  on  the  fifth  day.  Even  on  the  last 
4  days  of  the  14-day  fast  approximately  200  grams  of  dry  matter  were 
excreted  on  the  average  per  day.  In  the  fasts  after  submaintenance  feeding 
the  amount  of  dry  matter  on  the  first  day  was  much  smaller,  being  nearer 
1.2  kg.,  but  by  the  fifth  day  the  excretion  has  become  0.5  kg.,  as  in  the  other 
fasts.  With  the  two  small  steers  studied  after  submaintenance  feeding,  the 
dry  matter  was  not  determined  for  each  day  of  the  fast. 

The  analyses  for  steers  C  and  D  show  that  there  is  a  continued  loss  of 
dry  matter  of  ballast  throughout  the  entire  fast.  In  this  respect  the  fecal 
excretion  of  the  ruminant  is  strikingly  different  from  that  of  the  omnivorous 
man  or  dog,  due  without  doubt  to  the  large  intestinal  ballast. 

Inasmuch  as  these  animals  were  receiving  no  food,  the  total  loss  of  dry 
matter  during  the  various  lengths  of  the  fasts  is  important  *as  giving  an 
indication  of  at  least  the  minimum  amount  of  fill  existing  at  the  beginning 
of  the  experiment.  For  this  purpose  the  total  dry  matter  excreted  in  the 
feces  by  these  animals  has  been  recorded  in  Table  24,  together  with  data 
regarding  the  daily  amount  of  feed  consumed  during  the  week  prior  to  the 
fast.  In  the  longest  fast  of  14  days,  about  10  kg.  of  dry  matter  were  lost  by 
both  animals  on  a  feed-level  of  9  kg.  of  hay  and  3  kg.  of  meal.  If  it  is 
assumed  that  the  dry  matter  in  the  feces  of  the  steer  represents  on  the 
average  20  per  cent  of  the  total  fill,  it  can  be  seen  that  at  the  start  of  this 
14-day  fast  the  fill  must  have  amounted  to  at  least  50  kg.  The  evidence, 


FECES 


95 


however,  is  strikingly  to  the  effect  that  the  fill  contains  more  than  80  per 
cent  of  water.  The  estimate  of  50  kg.,  therefore,  undoubtedly  represents  a 
minimum  amount.  Furthermore,  it  is  clear  that  this  estimate  does  not 
include  all  the  fecal  material,  for  some  must  have  been  retained.® 


Table  24. — Total  weight  of  dry  matter  excreted  in  feces  during  fasts  of  5  to  14  days 


Dates  of  fasts 

Daily  ration 
prior  to  fast 

Steer  C 

Steer  D 

Days 

fast¬ 

ing 

Total 

dry 

matter 

Days 

fast¬ 

ing 

Total 

dry 

matter 

Hay 

Meal 

kg. 

kg. 

kg. 

kg. 

Dec. 

6  to  13,  1921 . 

8.5 

1.4 

7 

8.02 

7 

6.99 

Jan. 

4 

14,  1922 . 

7.0 

6.0 

10 

8.08 

10 

8.18 

Apr. 

17 

May  1,  1922 . 

9.0 

3.0 

14 

10.25 

14 

9.95 

June 

1 

7,  1922 . 

8.5 

4.0 

6 

8.36 

5 

6.98 

Nov. 

6 

16,  1922 . 

Pasture 

9 

6.52 

8 

6.18 

Nov. 

4 

10,  1923 . 

Pasture 

5 

7.01 

5 

6.23 

Mar. 

3 

13,  1924 . 

4.5 

10 

4.56 

9 

5.05 

In  the  6-day  fast  in  June  1922,  steer  C  excreted  8.36  kg.  of  dry  matter, 
or  within  2  kg.  of  that  excreted  in  14  days.  The  ration  prior  to  this  fast 
contained  0.5  kg.  less  of  hay  and  1  kg.  more  of  meal.  After  pasture,  smaller 
amounts  of  dry  matter  were  excreted  and,  as  is  to  be  expected,  even  in  the 
10-day  fast  following  submaintenance  feeding  a  total  of  but  4.5  and  5  kg. 
of  dry  matter  were  excreted  by  steers  C  and  D,  respectively.  In  this  case 
the  feed-level  was  4.5  kg.  of  hay. 

It  is  perhaps  to  be  regretted  that  the  animals  were  not  slaughtered  at  the 
end  of  the  fasting-periods,  particularly  at  the  end  of  the  long  fasts,  in  order 
to  note  the  contents  of  the  intestinal  tract.  Indeed,  a  study  of  the  contents 
of  the  intestinal  tract  after  various  rations  is  imperatively  needed,  not  only 
to  give  information  regarding  the  physiological  processes  of  digestion,  but 
likewise  regarding  the  proportion  of  fill  to  body-weight  on  varying  rations. 

Nitrogen  in  Feces 

The  nitrogen  excretion  in  the  feces  is  of  greatest  significance  in  consider¬ 
ing  the  nitrogen  loss  during  fasting  and  in  establishing  a  nitrogen  balance, 
in  which  the  nitrogen  in  the  urine  enters  particularly  into  the  calculation. 
It  is  important,  however,  to  note  also  the  rate  of  nitrogen  loss  in  the  fasting 
feces  (presumably  in  large  part  in  the  form  of  undigested  material)  and  the 
effect  of  the  previous  ration  of  hay  and  meal  or  of  green  grass.  In  Table  25, 
therefore,  are  recorded  the  average  daily  weights  of  nitrogen  excreted  in 
feces  for  the  feed  periods  prior  to  the  fast,  and  the  total  fecal  nitrogen  for 

°  Colin  (Traite  de  Physiologie  Comparee  des  Animaux,  3d  ed.,  Paris,  1888,  2,  p.  693)  found 
that  a  horse,  which  was  slaughtered  after  having  fasted  for  30  days,  had  26.2  kg.  of  fill  in  the 
intestinal  tract.  This  finding  emphasizes  the  necessity  for  bearing  in  mind  in  the  study  of  these 
large  ruminants  that  one  has  to  deal  continually  with  a  possible  ever-present  source  of  energy. 
Although  no  analysis  of  the  intestinal  contents  was  reported  by  Colin,  it  is  probable  that  the 
dry  matter  consisted  for  the  most  part  not  only  of  indigestible  material,  but  of  material  not  easily 
attacked  by  the  normal  intestinal  flora  of  the  horse. 


Table  25. — Daily  nitrogen  excretion  in  feces  before  and  during  fasts  of  5  to  14  days 


METABOLISM  OF  THE  FASTING  STEER 


1  Average  daily  fecal  nitrogen  for  from  1  to  2  weeks  on  feed  before  fast.  For  exact  dates  represented  see  Table  22,  p.  92. 

2  No  nitrogen  analysis  was  made  for  the  sixth  day  of  this  fast.  The  analysis  of  the  composite  sample  for  June  1  to  7  gave  0.292  p.  ct.  nitrogen  in  the 
fresh  feces.  On  the  basis  of  this  analysis  the  total  fecal  nitrogen  for  6  days  would  be  145.8  gm.,  and  the  fecal  nitrogen  on  the  sixth  day  would  be  8.8  gm. 


URINE 


97 


each  day  of  the  fasts.  The  daily  weights  of  fecal  nitrogen  are  also  given 
in  Fig.  4  for  the  fasts  in  April  and  November  1922  and  March  1924.  Special 
use  of  these  data  is  made  in  considering  the  total  nitrogen  loss.  (See  p.  127.) 

The  only  data  available  for  comparison  regarding  the  fecal  excretion  of 
large  ruminants  during  fasting  are  those  reported  by  Grouven  in  1864.°  The 
daily  weights  of  feces  and  the  contents  of  dry  matter  and  nitrogen  were 
determined  by  him  in  the  case  of  a  black  ox  which  fasted  for  8  days,  a 
brown  ox  which  fasted  for  5  days,  and  ox  I,  which  fasted  for  4  days.  The 
findings  with  steers  C,  D,  E,  and  F  completely  confirm  those  of  Grouven. 
Thus,  Grouven  noted  that  the  daily  weights  of  feces  decreased  as  the  fast 
prpgressed,  the  largest  amounts  occurring  on  the  first  day  and  some  feces 
being  excreted  every  day  throughout  the  fast.  Increasing  percentages  of 
dry  matter  and  nitrogen  were  also  noted  by  him  in  the  case  of  the  black 
and  the  brown  oxen,  but  in  the  case  of  ox  I  there  was  practically  no  change 
in  the  percentage  of  nitrogen.  The  black  and  the  brown  oxen  were  slaugh¬ 
tered  after  their  fasts,  and  it  was  found  that  the  contents  of  the  intestinal 
tract  represented  10.7  per  cent  and  14.2  per  cent,  respectively,  of  the  total 
live  weight  of  the  animal. 

URINE 

The  urine  is  the  path  for  the  loss  of  considerable  volumes  of  water  and 
the  chief  outlet  for  metabolized  nitrogen.  Indeed,  in  nutrition  experiments 
with  steers,  the  nitrogen  output  in  the  urine  has,  for  many  years,  been 
accepted  as  the  best  measure  of  protein  metabolism.  In  connection  with 
these  fasting  experiments,  therefore,  the  amount,  frequency,  and  regularity 
of  urination  was  studied  and  an  extensive  chemical  analysis  was  made  of 
the  constituents  of  the  urine  during  fasting. 

The  collection  of  the  urine  for  such  studies  requires  special  technique. 
With  steers  the  technique  is  relatively  simple,  the  essential  requirements 
being  the  confinement  of  the  animal  in  a  stall  and  the  use  of  a  harness  and 
a  urine  funnel,  which  is  connected  with  previously  weighed  bottles  in  the 
basement  beneath  the  stall.  With  cows  the  technique  is  more  complicated. 
Not  infrequently  urine  and  feces  are  collected  together,  and  since  the  urine 
contains  metabolized  nitrogen  and  the  feces  contain  undigested  nitrogen,  the 
combined  collection  of  urine  and  feces  introduces  an  element  of  uncertainty 
into  the  determination  of  the  nitrogen  actually  derived  from  body-tissue. 
During  this  research  on  fasting  the  steers  wore  urine  funnels  for  months  at 
a  time,  and  doubtless  some  of  the  experiments  represent  the  longest  con¬ 
tinuous  periods  in  which  stall  feeding,  metabolism  experiments,  and  con¬ 
tinuous  collection  of  urine  have  been  carried  out. 

In  the  collection  of  the  urine  during  the  fasting  periods  attention  was 
given  to  the  volume  and  the  time  of  each  individual  urination,  as  well  as 
to  the  total  volume  passed  daily.  Ordinarily  the  data  regarding  the  amount 
of  urine  excreted  are  reported  on  the  24-hour  basis.  For  a  general  study  of 
the  volume  of  urine,  24-hour  collections  of  urine  are  perhaps  sufficiently 
satisfactory.  Since  the  steer  will  not  voluntarily  empty  the  bladder  exactly 
at  the  end  of  each  24  hours,  however,  the  apportionment  of  the  urinations 

°  Grouven,  loc.  cit.,  pp.  127  et  seq. 


98 


METABOLISM  OF  THE  FASTING  STEER 


during  the  24-hour  periods  presents  difficulty  at  times.  Thus,  if  urine  is 
passed  a  few  minutes  after  2  p.  m.,  the  beginning  of  the  24-hour  period  in 
most  of  our  fasting  experiments,  it  is  a  question  whether  this  amount  should 
be  credited  to  the  previous  24-hour  period.  Special  discussion  of  this  point 
will  be  given  subsequently  (see  p.  110)  .  In  most  instances  the  exact  time  of 
each  voiding  was  recorded,  so  that  it  is  possible  to  ascribe  a  certain  urinary 
volume  to  a  definite  period  of  time  since  the  last  urination.  These  time 
records  make  possible  a  closer  approximation  to  the  true  amounts  of  urine 
voided  in  any  given  time  and  are  of  special  value  in  the  more  accurate 
chemical  analysis  of  the  urine  and  particularly  in  studying  the  influence  of 
prolonged  fasting  and  the  differences  between  animals.  Indeed,  many  of 
the  data  regarding  the  chemical  constituents  of  the  urine  have  been  reported 
on  the  hourly  basis  (see  Tables  28  and  29,  pp.  108  to  111). 

The  physical  properties  of  the  urine,  its  color,  odor,  and  density,  were 
frequently  determined.  A  study  was  also  made  during  some  of  the  later 
fasting  periods  of  the  reaction  of  each  urination  to  litmus  paper,  in  order 
to  determine  at  what  time  in  the  course  of  the  fast  the  normal  alkaline  urine 
of  the  steer  becomes  the  acid  urine  of  the  carnivorous  animal.  The  pro¬ 
cedure  was  as  follows:  Twice  daily  the  urine  funnel  and  the  urine  hose  were 
washed  out  with  distilled  water.  At  each  urination  several  pieces  of  litmus 

Table  26. — Daily  excretion  of  urine  during  2-day  fasts  and  three  days  with  feed  prior  to  fasts, 

steers  C  and  D 


Steer  and  dates 
of  fasts 
(1923) 

Days  before  fast 

Days  fasting 

3 

2 

1 

1 

2 

Steer  C: 

kg. 

°  C. 

kg. 

°C. 

kg. 

°  C. 

kg. 

0  C. 

kg. 

0  C. 

Jan.  3  to  6 . .  . 

4.92 

15 

5.34 

12 

5.47 

11 

2.67 

6 

>3.30 

9 

Jan.  15  17... 

5.16 

25 

4.88 

20 

5.86 

26 

4.27 

29 

3.06 

12 

Jan.  21  23 . . . 

2.83 

28 

3.92 

27 

6.54 

29 

3.74 

28 

2.88 

7 

Jan.  28  30. . . 

3.32 

11 

4.87 

26 

6.19 

11 

5.28 

8 

2.20 

25 

Feb.  5  7 ... 

5.56 

12 

5.16 

4 

4.71 

7 

4.81 

6 

2.80 

5 

Feb.  11  13.  . . 

3.18 

8 

4.08 

10 

5.42 

11 

5.16 

8 

3.20 

8 

Feb.  18  20. . . 

4.16 

-  3 

5.20 

3 

4.90 

7 

4^86 

4 

3.50 

0 

Mar.  1  3 .  . . 

5.18 

12 

6.06 

13 

5.38 

11 

5.06 

12 

3.42 

14 

Mar.  8  10.  .  . 

3.18 

4 

4.68 

3 

4.84 

4 

4.04 

4 

2.17 

6 

Mar.  15  17.  . . 

4.18 

10 

4.08 

7 

3.90 

5 

4.58 

8 

2.77 

8 

Mar.  22  24... 

3.68 

19 

4.36 

24 

4.40 

27 

4.18 

26 

2.70 

22 

Steer  D: 

Jan.  9  to  12 .  .  . 

4.84 

8 

2  5.96 

11 

3.68 

12 

3.97 

13 

12.88 

9 

Jan.  17  19. . . 

3.82 

26 

4.77 

29 

5.18 

12 

5.21 

12 

2.27 

28 

Jan.  25  27. . . 

5.12 

7 

5.55 

13 

4.75 

11 

4.09 

11 

3.08 

26 

Feb.  1  3.  . . 

3.47 

25 

4.26 

28 

4.09 

23 

4.17 

23 

2.25 

12 

Feb.  8  10... 

4.17 

6 

4.57 

5 

3.74 

7 

3.97 

8 

2.18 

10 

Feb.  14  16... 

3.60 

8 

4.41 

8 

6.12 

6 

5.04 

-  3 

2.58 

-  3 

Feb.  22  24 .  . . 

4.72 

0 

5.43 

6 

5.42 

6 

5.50 

2 

2.08 

-  2 

Mar.  5  7 . . . 

4.56 

14 

5.62 

11 

4.84 

5 

4.58 

4 

2.17 

3 

Mar.  13  15... 

5.29 

5 

4.02 

7 

3.40 

10 

4.00 

7 

2.28 

5 

Mar.  20  22 .  . . 

6.12 

7 

4.93 

24 

4.76 

19 

2.91 

24 

2.04 

27 

1  Steers  C  and  D  fasted  a  third  day  on  Jan.  5-6  and  Jan.  11-12,  respectively;  steer  C  voided 
2.66  kg.  of  urine  and  steer  D  5.16  kg. 

1  Steer  went  24  hours  without  food  preparatory  to  a  proposed  respiration  experiment,  but 
the  experiment  was  not  made. 


URINE 


99 


paper  were  held  under  the  end  of  the  hose,  enough  urine  always  being  left 
in  the  elbow  of  the  hose  after  urination  to  wet  the  papers  thoroughly.  The 
hose  was  well  drained  after  each  litmus  test.  As  a  precaution  against  change 
in  urine,  the  test  should  be  made  as  soon  as  possible  after  the  urine  is  passed. 

Influence  of  Fasting  on  Amounts  of  Urine  Excreted 
Amounts  per  24  Hours  and  per  Hour 

The  amounts  of  urine  excreted  daily  during  the  series  of  2-day  and  3-day 
fasts  in  1923  and  during  3  days  just  previous  to  each  of  these  fasts  are 
recorded  in  Table  26,  together  with  the  average  stall  temperature  during 
the  same  24  hours.  It  will  be  recalled  that  in  the  feeding-periods  between 
these  intermittent  fasts  the  animals  received  a  maintenance  ration  of  9  kg. 
of  hay  and  2  kg.  of  meal  daily.  The  nutritive  level  was  therefore  held  fairly 
constant.  The  most  striking  feature  of  this  table  is  the  distinctly  lower 
amounts  of  urine  excreted  on  the  second  day  of  fasting.  On  the  first  day 
occasional  decreases  in  the  24-hour  weights  of  urine  are  observed,  but  for 
the  most  part  the  amounts  are  essentially  the  same  as  those  noted  prior  to 
the  fasting  periods.®  The  amount  of  urination,  furthermore,  is  seemingly 
wholly  independent  of  environmental  temperature. 

The  interest  centers  chiefly,  however,  in  the  data  for  the  fasts  of  5  to  14 
days’  duration.  The  daily  weights  of  urine  during  these  fasts  and  for  3  days 
with  feed  before  each  of  the  fasts  are  given  in  Table  27.  Since  these  fasts 
followed  maintenance,  submaintenance,  or  pasture  feeding,  and  since  steers 
E  and  F  were  much  smaller  and  younger  than  steers  C  and  D,  variations  in 
the  urinary  excretion  are  naturally  to  be  expected.  Finally,  it  must  not  be 
forgotten  in  the  analysis  of  these  data  that  the  24-hour  weight  of  urine  may 
actually  represent  a  period  much  shorter  or  longer  than  24  hours.  Obvi¬ 
ously,  however,  the  more  frequent  the  urination  the  greater  the  likelihood 
of  the  24-hour  collection  representing  the  true  24-hour  excretion. 

In  the  three  days  prior  to  fasting,  steer  C  excreted  a  maximum  daily 
amount  of  10.92  kg.  of  urine  just  preceding  the  fast  in  January  1922,  and  a 
minimum  amount  of  2.22  kg.  prior  to  the  fast  following  submaintenance 
feeding  in  March  1924.  These  extremes  are  not  noted  with  steer  D,  the 
highest  24-hour  amount  excreted  by  him  being  6.71  kg.  prior  to  the  fast  in 
January  1922,  and  the  lowest  being  3.70  kg.  prior  to  the  March  fast.  In 
general,  as  is  to  be  expected,  the  weights  of  urine  during  the  3  days  on  the 
submaintenance  ration,  that  is,  in  March  1924,  are  considerably  lower  than 
those  during  the  three  days  preceding  the  other  fasts.  Steers  E  and  F  prior 
to  their  fasts  excreted  small  amounts,  explainable  on  the  two  grounds  that 
they  were  smaller  animals  and  were  on  submaintenance  rations. 

During  the  actual  fasting  periods  the  maximum  24-hour  excretion  on  the 
first  day  of  the  fasts  following  maintenance  or  pasture  feeding  was  13.03 
kg.,  noted  with  steer  D.  The  daily  weights  of  urine  have  a  tendency  to 
decrease  as  the  fast  progresses.  With  steer  C,  minimum  values  are  usually 
recorded  on  the  fourth  day,  and  the  amounts  stay  reasonably  constant  from 

°  The  first  day  of  fasting  begins  at  2  p.  m.,  the  last  feed  having  been  given  between  7  and  8  a.  m. 
of  that  day.  The  first  feed  following  the  fast  was  given  during  the  last  3  hours  of  the  last  day 
of  fasting  (in  two  cases  during  the  last  6  hours).  This  refeed  usually  induced  a  relatively  liberal 
intake  of  water,  which  might  have  had  an  influence  upon  the  volume  of  urine  excreted. 


100 


METABOLISM  OF  THE  FASTING  STEER 


there  on,  even  when  the  fast  extends  to  14  days.  With  steer  D  the  regularity 
is  by  no  means  so  pronounced.  In  the  first  place,  as  large  an  amount  as  13 
kg.  was  found  on  the  first  day  of  the  January  fast.  Secondly,  a  very  high 
excretion  of  7.65  kg.  is  noted  on  the  tenth  day  of  the  fast  in  April  1922,  and 


Table  27. — Daily  excretion  of  urine  before  and  during  fasts  of  5  to  1 4  days 


Steer  and  dates  of  fasts 

Days  before  fast 

Days  fasting 

3 

2 

1 

1 

2 

3 

Steer  C: 

kg. 

O 

C. 

kg. 

O 

C. 

kg. 

}C. 

kg. 

°C. 

kg. 

°C. 

kg. 

°C. 

Dec.  6  to  13,  1921 . 

4. 

32 

9 

4.22 

7 

5 

.14 

7 

6.65 

5 

3.50 

5 

3.19 

15 

Jan.  4 

14,  1922 . 

6. 

51 

16 

6. 

73 

16 

10.92 

14 

9.41 

20 

4.46 

20 

3.35 

20 

Apr.  17 

May  1,  1922. . . 

4. 

03 

21 

4. 

65 

17 

4 

.54 

20 

5.25 

20 

7.72 

20 

5.26 

20 

June  1 

7, 1922 . 

5. 

61 

24 

4. 

97 

22 

4 

.71 

23 

7.11 

23 

9.98 

22 

4.12 

23 

Nov.  6 

16,  1922 . 

6.02 

3.57 

1.83 

Nov.  4 

10,  1923 . 

6.74 

4.31 

Mar.  3 

13,  1924 . 

2. 

74 

13 

2. 

22 

16 

3 

.74 

17 

1 

1.91 

14 

2.18 

16 

1.23 

16 

Steer  D: 

Dec.  6 

13,  1921 . 

4. 

42 

9 

4. 

12 

7 

5 

.08 

7 

8.59 

5 

2.96 

5 

1.49 

15 

Jan.  4 

14,  1922 . 

6. 

71 

16 

6. 

30 

16 

6.38 

14 

13.03 

20 

3.60 

20 

4.03 

20 

Apr.  17 

May  1,  1922... 

4. 

88 

21 

4. 

75 

17 

5 

.50 

20 

5.71 

20 

6.73 

20 

6.98 

20 

June  1 

6,  1922 . 

5. 

78 

24 

4. 

73 

22 

5 

.52 

23 

6.91 

23 

4.05 

22 

8.91 

23 

Nov.  6 

14,  1922 . 

6.30 

2.93 

2.82 

Nov.  4 

9,  1923 . 

9.17 

3.56 

Mar.  3 

12,  1924 . 

3. 

70 

13 

3. 

90 

16 

4 

.03 

17 

1 

3.20 

14 

4.82 

16 

1.40 

16 

Steer  E: 

Feb.  12 

17,  1924 . 

1. 

76 

12 

2. 

04 

12 

1.93 

13 

1.34 

16 

5.00 

15 

1.14 

16 

Steer  F: 

Feb.  12 

18,  1924 . 

1. 

37 

12 

1. 

72 

12 

1 

.70 

13 

1.40 

16 

1.21 

15 

0.91 

16 

Days  fasting 

oteer  ana  dates  ol  lasts 

4 

5 

6 

7 

8 

9 

Steer  C: 

kg. 

°( 

n 

kg. 

°( 

nr 

kg. 

°C 

kg. 

°C. 

kg. 

0  C. 

kg. 

°C. 

Dec.  6  to  13.  1921 . 

1. 

97 

20 

2 

98 

18 

2.67 

17 

1.67 

20 

Jan.  4 

14,  1922 . 

1. 

68 

21 

2. 

36 

24 

4.64 

20 

2.13 

20 

1.67 

21 

1.60 

23 

Apr.  17 

May  1,  1922.  .  . 

3. 

16 

15 

2 

03 

20 

3  84 

22 

2  18 

22 

1.92 

22 

2.09 

23 

June  1 

7,  1922 . 

2. 

55 

2.f> 

3 

09 

27 

2.40 

26 

Nov.  6 

16,  1922 . 

2. 

99 

2. 

88 

1.93 

2.68 

2.66 

2.67 

.... 

Nov.  4 

10,  1923 . 

2 

70 

2 

91 

3.32 

Mar.  3 

13,  1924 . 

2. 

54 

16 

0. 

65 

14 

0.94 

16 

2.23 

18 

1.73 

14 

1.64 

16 

Steer  D: 

Dec.  6 

to  13,  1921 . 

5. 

55 

20 

1 

83 

18 

1  47 

17 

5.02 

20 

Jan.  4 

14,  1922 . 

3. 

19 

21 

3. 

19 

24 

3.07 

20 

4.33 

20 

1.89 

21 

1.36 

23 

Apr.  17  to  May  1,  1922.  .  . 

3. 

20 

15 

2. 

43 

20 

2.29 

22 

1.57 

22 

1.87 

22 

1.92 

23 

June  1 

6,  1922 . 

3. 

01 

25 

7. 

40 

27 

Nov.  6 

14,  1922 . 

3. 

31 

5. 

72 

3.94 

. 

2.11 

2.02 

. . . . 

Nov.  4 

9,  1923 . 

3 

23 

2. 

66 

Mar.  3 

12,  1924 . 

3. 

25 

16 

3. 

15 

14 

1.74 

16 

3.35 

18 

2.50 

14 

1.25 

16 

Steer  E: 

Feb.  12  to  17.  1924 . 

5  27 

15 

Steer  F: 

Feb.  12  to  18.  1924 . 

1. 

09 

15 

1. 

23 

14 

1  This  value  represents  a  period  of  only  17  hours,  from  2  p.  m.  to  7  a.  m. 


URINE 


101 


Table  27. — Daily  excretion  of  urine  before  and  during  fasts  of  5  to  1 4  days — Continued 


Steer  and  dates  of  fasts 

Days  fasting 

10 

11 

12 

13 

14 

Steer  C: 

Jan.  4  to  14,  1922 . 

kg. 

1.86 

2.12 

2.23 

2.47 

7.65 

°  C. 
23 
20 
16 

23 

20 

kg. 

°  C. 

kg. 

0  C. 

kg. 

°  C. 

kg. 

°  C. 

Apr.  17  May  1,  1922 . 

Mar.  3  13,  1924 . 

4.63 

22 

2.01 

21 

1.61 

21 

2.35 

21 

Steer  D: 

Jan.  4  14,  1922 . 

Apr.  17  May  1,  1922 . 

2.32 

22 

3.81 

21 

5.68 

21 

1.90 

21 

an  extremely  low  amount  of  1.49  kg.  on  the  third  day  of  the  fast  in  Decem¬ 
ber  1921.  This  animal  is  characterized,  therefore,  by  a  much  greater  irregu¬ 
larity  in  the  excretion  of  urine.  In  the  fasts  following  pasture,  when  the 
body  was  full  of  a  succulent  feed,  the  results  are  not  strikingly  different 
from  those  noted  in  the  fasts  following  maintenance  feeding.  But  in  the 
fasts  following  submaintenance  feeding  in  March  1924  a  much  lower  level 
of  excretion  was  noted  throughout  practically  the  entire  fasting  period  with 
both  animals.  This  finding  is  in  full  conformity  with  the  decreased  volumes 
observed  prior  to  this  fast. 

The  hourly  excretion  of  urine  has  likewise  been  computed  for  these  fasts 
of  5  to  14  days,  and  the  data  have  been  recorded  in  Tables  28  and  29 
(pp.  108  to  111),  from  which  it  can  be  seen  that  the  volume  of  urine  excreted 
per  hour  during  fasting  undergoes  enormous  changes.  The  largest  hourly 
excretion  was  noted  with  both  steers  on  the  same  date,  January  4-5,  1922, 
being  384  c.  c.  in  the  case  of  steer  C  and  535  c.  c.  in  the  case  of  steer  D. 
The  lowest  values  occur,  as  perhaps  is  to  be  expected,  during  the  fasts  in 
March  1924,  following  submaintenance  feeding,  when  the  hourly  excretion 
of  steer  C  was  as  low  as  52  c.  c.  on  March  12-13,  and  that  of  steer  D  was 
as  low  as  46  c.  c.  on  March  5-6.  With  steers  E  and  F  in  their  fasts  follow¬ 
ing  submaintenance  rations  the  hourly  values  likewise  vary  considerably. 
A  careful  analysis  of  this  decrease  is  possible  only  when  the  amounts  of 
drinking-water  consumed  are  taken  into  consideration.  In  general,  when 
the  steer  is  on  submaintenance  rations,  the  water  intake  is  smaller  and  the 
volume  of  urine  is  naturally  considerably  smaller. 

The  Frequency  and  Amount  of  Individual  Urinations  During  Fasting 

A  study  of  the  influence  of  fasting  and  the  amount  of  drinking-water 
upon  the  frequency  of  urination  and  the  volume  of  each  individual  urination 
was  possible  in  all  of  the  fasts  of  5  to  14  days.  The  14-day  fast  in  April 
1922,  after  maintenance  feeding,  the  fast  after  pasture  feeding  in  Novem¬ 
ber  1922,  and  the  fast  following  submaintenance  feeding  in  March  1924, 
have  been  selected  as  illustrations  for  this  study.  These  three  represent 
typical  fasts  under  the  varying  feed  conditions,  the  fast  in  April  following 
maintenance  rations  being  typical  of  the  larger  number  of  the  fasts.  The 
pertinent  data  have  been  charted  in  Fig.  7.  The  curves  show  graphically 


102 


METABOLISM  OF  THE  FASTING  STEER 


the  times  of  urination  and  the  actual  amounts  involved.  The  figures  in  the 
upper  row  above  each  curve  represent  the  total  weights  of  drinking-water 
during  the  24-hour  periods  and  the  figures  in  the  lower  row  the  total  weights 
of  urine. 

Gfn*. 

O 


Fig.  7. — Individual  urinations  of  steers  C  and  D  during  fasts  in  April  and  November  1922  and 

March  1924 


The  two  curves  at  the  bottom  of  the  chart  represent  the  fasts  in  April  1922,  which  followed 
maintenance  feeding.  Those  in  the  center  are  for  the  fasts  in  November  1922,  following 
pasture  feeding,  and  the  two  at  the  top  are  for  the  fasts  in  March  1924,  following  submain¬ 
tenance  feeding.  The  figures  in  the  upper  row  above  each  curve  represent  the  amounts  of 
drinking-water  (in  kilograms)  taken  in  every  case  at  the  beginning  of  the  24-hour  period.  The 
figures  in  the  lower  row  represent  the  total  kilograms  of  urine  voided  during  the  24-hour 
periods. 

The  frequency  of  urination  varied  considerably  with  steers  C  and  D.  In 
general,  steer  D  urinated  more  frequently  throughout  the  day  than  did 
steer  C,  and  the  total  volumes  were  somewhat  different.  Thus,  the  total 
amount  of  urine  excreted  by  steer  C  in  the  14-day  fast  was  46.17  kg.  and 
by  steer  D  was  54.06  kg.  On  those  days  when  peaks  in  the  curve  occur, 
showing  large  volumes  of  urine,  one  finds  a  correlation  with  water  intake 
only  rarely.  Thus,  in  the  March  fast,  at  the  beginning  of  the  seventh  day, 


URINE 


103 


when  steer  D  drank  11.2  kg.  of  water,  there  was  but  a  small  increase  in  the 
24-hour  amount  of  urine  excreted.  On  the  two  following  days,  when  he 
drank  no  water,  the  total  amount  of  urine  decreased,  to  be  sure,  but  not  at 
all  in  proportion  to  the  decrease  in  the  water  intake.  On  the  other  hand, 
with  steer  D,  on  the  fifth  day  of  the  fast  in  November  1922,  after  pasture, 
an  intake  of  water  of  24.4  kg.  is  followed  by  a  very  large  urination.  On 
the  whole,  however,  there  is  no  distinct  evidence  of  a  pronounced  relationship 
between  water  intake  and  volume  of  urine. 

The  maximum  individual  urinations  occurred  with  steer  D.  In  the  fast 
following  pasture  3,048  grams  were  voided  on  the  fifth  day  and  on  the  second 
and  third  days  of  the  April  fast  3,122  and  3,151  grams,  respectively,  were 
voided.  Very  small  amounts  were  also  frequently  passed  by  steer  D.  Thus, 
as  early  as  on  the  seventh  day  of  the  April  fast,  an  amount  less  than  100 
grams  was  passed,  and  on  three  subsequent  days  in  this  same  fast  amounts 
under  100  grams  were  also  passed.  With  steer  C  on  the  first  day  of  the 
April  fast  a  small  voiding  of  99  grams  occurred.  Large  changes  in  the  con¬ 
tent  of  the  bladder  needed  to  stimulate  voiding  thus  seem  possible,  even 
under  these  restricted  conditions.  A  possible  explanation  of  the  variability 
in  the  individual  urinations  might  be  the  temperature  to  which  the  animals 
were  exposed.  (See  the  records  of  stall  temperatures  in  Table  27,  p.  100.)  A 
careful  examination  of  the  records,  however,  shows  no  correlation  between 
the  two  factors.  Usually  both  animals  were  essentially  at  the  same  tem¬ 
perature,  not  far  from  15°  to  20°  C.,  the  entire  time.  A  study  of  the  influ¬ 
ence  of  environmental  temperature  upon  the  urinary  volume  would  be  more 
significant,  if  made  on  days  when  the  steer  was  receiving  a  constant  ration, 
prior  to  any  fasting.  Our  evidence  is  not  complete  for  this  purpose,  but,  so 
far  as  it  goes,  there  is  nothing  to  indicate  any  relationship  between  the 
environmental  temperature  and  the  weight  of  urine. 

Relation  Between  Volume  and  Dry  Matter  op  Urine 

The  necessity  for  the  addition  of  a  preservative  to  the  urines  of  these 
steers  and  the  length  of  time  that  the  urines  had  to  be  stored  made  late  deter¬ 
minations  of  the  specific  gravity  or  total  solids  unsatisfactory,  and  hence  our 
evidence  on  the  relation  between  the  volume  and  the  dry  matter  of  urine  is 
somewhat  uncertain.  From  our  observations  in  the  research  on  undernutri¬ 
tion  in  steers  it  was  clear  that  the  volumes  of  urine,  as  was  the  case  with 
the  urines  of  these  fasting  steers,  were  not  profoundly  affected  by  variations 
in  the  amount  of  nitrogen  in  the  urine,  and  surprisingly  little  affected  by 
relatively  large  changes  in  the  amount  of  drinking-water  consumed. 

Physical  Properties  of  the  Urine 

In  general,  during  normal  feeding,  such  as  usually  preceded  a  fast,  the 
urine  was  of  a  dilute  yellowish-brown  color,  tending  towards  opaqueness  in 
proportion  to  the  relative  daily  amount  voided.  Thus,  when  the  amount 
was  extraordinarily  large,  the  urine,  because  diluted,  was  lighter  colored 
than  when  the  amount  was  unusually  small  and  concentrated.  As  the  fast 
progressed  and  less  water  was  consumed  by  the  animal,  the  volume  of  urine 
usually  decreased  and  the  color  became  darker,  very  small  volumes  often 
being  almost  black  in  appearance.  The  darker  the  color  of  the  urine  the 


104 


METABOLISM  OF  THE  FASTING  STEER 


more  intense  and  offensive  became  the  odor,  probably  because  the  urine  was 
voided  at  longer  intervals  and  the  decomposition  in  the  bladder  was  further 
advanced  before  the  urine  was  voided.  (See  p.  121.) 

Chemistry  of  the  Urine 

The  chemical  analysis  of  the  urine,  particularly  with  reference  to  the 
various  nitrogenous  ingredients  and  the  apportionment  of  the  total  nitrogen 
among  the  various  compounds,  has  proved  of  great  physiological  interest 
and  of  inestimable  chemical  value  in  the  case  of  humans.  The  possibility 
of  studying  the  urinary  output  of  a  large  ruminant  during  fasting  and  com¬ 
paring  the  results  with  analyses  of  the  characteristically  different  urines 
prior  to  fasting  made  such  a  study  an  important  part  of  our  program.  Dr. 
Thorne  M.  Carpenter,  of  the  Nutrition  Laboratory,  has  undertaken  the 
analysis  of  such  samples  of  urine  as  could  be  secured  from  our  fasting 
steers,  and  the  following  discussion  is  for  the  most  part  based  upon  a  detailed 
report  which  he  is  soon  to  publish.  Preliminary  communications  on  this 
subject  have  already  been  made  by  Dr.  Carpenter.® 

Urine  Analyses  by  Other  Investigators 

The  many  characteristics  of  the  urine  of  herbivora  obviously  different 
from  the  characteristics  of  human  urine,  such  as  the  high  alkaline  reaction, 
the  presence  of  carbonates,  and  differences  in  color  and  odor,  would  naturally 
suggest  that  the  urine  of  herbivora  is  a  physiological  fluid  of  vastly  different 
chemical  nature  from  that  excreted  by  humans.  That  this  problem  has 
already  interested  research  workers  is  evidenced  by  the  fact  that  as  far 
back  as  1864  Grouven6  devoted  not  a  little  attention  to  the  subject,  but 
unfortunately  with  very  defective  methods.  Indeed,  Grouven  was  the  first 
to  collect  and  analyze  the  urines  of  fasting  steers.  The  weight,  specific 
gravity,  total  nitrogen,  dry  matter,  and  ash  were  determined.  In  a  few 
instances  the  hippuric  acid  was  estimated.  Five  animals  were  studied  in 
9  fasts  which  varied  from  431/2  hours  to  8  days  in  length.  All  of  the  fasts 
were  preceded  by  feeding  periods  of  from  3  to  14  days,  the  ration  usually 
being  circa.  3.5  kg.  of  rye  straw.  In  an  8-day  fast  of  an  ox  weighing  522 
kg.  the  nitrogen  elimination  on  the  first  two  days  was  32  gm.  per  day,  on 
the  third  and  fourth  days  54  gm.,  on  the  fifth  and  sixth  days  40  gm.,  and 
on  the  seventh  and  eighth  days  68  gm.  In  a  5-day  fast  with  an  ox  weighing 
420  kg.  the  nitrogen  elimination  was  42  gm.  per  day  on  the  first  two  days, 
54  gm.  on  the  next  two  days,  and  51  gm.  on  the  last  day.  With  an  animal 
weighing  535  kg.  the  nitrogen  excretion  varied  from  20  gm.  on  the  first  day 
of  fasting  to  50  gm.  on  the  fourth  day.  The  other  fasts  were  of  3  days’ 
duration  or  less.  In  several  of  them  the  nitrogen  excretion  was  extremely 
low,  the  lowest  amount  being  17  gm.  on  the  first  day. 

The  subject  then  remained  almost  entirely  unstudied  until  1906,  when 
Baer  reported  the  effect  of  the  withdrawal  of  carbohydrate  upon  various 
animals,  with  reference  to  the  onset  of  acidosis.  Among  the  animals  used 

°  Carpenter,  Journ.  Biol.  Chem.,  1923,  55,  p.  iii;  ibid.,  Proc.  Nat.  Acad.  Sci.,  1925,  11,  p.  155. 

b  Grouven,  Physiologisch-chemische  Futterungsversuche.  Zweiter  Bericht  uber  die  Arbeiten 
der  agrikulturchemischen  Versuchsstation  zu  Salmiinde,  Berlin,  1864,  pp.  127  to  195. 


URINE 


105 


were  3  goats  which  fasted  for  a  period  of  3  days  and  then  were  given 
phlorizin.  The  details  of  this  study  must  be  secured  from  the  original 
report.0  Of  special  interest  is  the  24-hour  urinary  nitrogen  per  kilogram  of 
body-weight,  which  calculation  shows  to  be  0.28  and  0.29  gm.  on  the  first 
fasting  day,  i.  e.,  a  nitrogen-level  considerably  higher  than  that  found  with 
our  fasting  steers.  The  ammonia  constituted  a  small  proportion  of  the  total 
nitrogen-content,  with  but  little  evidence  of  an  acidosis.  The  excretion  of 
acetone  was  small  and  remained  essentially  constant  during  the  fast. 

Prayon,6  in  1910,  studied  the  creatinine  excretion  in  the  urines  of  an  ox, 
a  bull,  and  a  mare  during  periods  of  normal  feeding  and  during  a  3-day 
fasting  period.  He  determined  only  the  percentage  content  of  creatinine, 
however,  and  computed  the  weight  of  the  creatinine  from  an  assumed  volume 
of  urine  per  day. 

In  1920,  Blatherwick,®  studying  the  regulation  of  neutrality  in  the  blood 
of  cattle,  made  determinations  on  the  plasma  and  urine  of  a  cow  which 
fasted  and  practically  went  without  water  for  7  days.  The  results  of  the 
urine  analyses  are  reported  per  100  c.  c.  of  urine.  The  ammonia  increased 
from  7  to  13  mg.  in  4  days  and  the  phosphorus  from  20.6  to  156.3  mg.  in 
7  days.  The  author  concludes  that  the  only  evidence  of  acidosis  is  the  fact 
that  the  phosphorus  in  the  blood  plasma  showed  an  increase  in  the  early 
part  of  the  fast. 

In  this  same  year  Peters'* *  published  the  results  of  his  study  of  the  urines 
of  normal  goats  upon  different  diets,  fasting,  and  after  feeding  with  acid  and 
alkali,  with  special  reference  to  the  acidity  reaction,  the  titratable  alkalinity, 
the  hydrogen-ion  concentration,  and  the  excretion  of  ammonia  and  chlorides. 
Two  goats  fasted  for  24  hours  and  one  goat  fasted  for  48  hours.  The  urines 
became  more  acid  as  the  result  of  fasting,  and  in  each  instance  reached  the 
greatest  acidity  on  the  day  following  the  fasting  period.  The  ammonia 
excretion  on  the  first  day  of  fasting  was  0.032  gm.  per  24  hours  with  a  goat 
weighing  26  kg.  and  0.072  gm.  with  a  goat  weighing  24  kg.  The  lighter 
weight  goat  also  fasted  a  second  day,  when  the  ammonia  excretion  was 
0.105  gm. 

Two  communications  were  made  by  Palladine  in  1924,  who  studied  par¬ 
ticularly  the  creatine  and  the  creatinine  in  the  urine  of  adult  sheep  fasting 
for  various  lengths  of  time.  A  sheep  weighing  88  kg.  had  lost  12  kg.  after 
a  9-day  fast.  At  the  beginning  of  the  fast  the  total  nitrogen  in  the  urine 
amounted  to  11.26  gm.  for  24  hours,  and  at  the  end  of  the  fast  to  5.4  gm. 
Creatinine  was  excreted  during  the  entire  fast,  as  was  creatine  after  the 
first  day.  The  urinary  nitrogen  per  kilogram  of  body-weight  per  24  hours 
was  0.128  gm.  on  the  first  day  of  the  fast  and  0.071  gm.  on  the  last  day. 
The  creatinine  coefficient  was  19.0  mg.  on  the  first  day  and  18.1  mg.  on  the 

°  Baer,  Arch.  f.  exp.  Path.  u.  Pharm.,  1906,  54,  p.  153. 

6  Prayon,  Methoden  zur  Bestimmung  des  Kreatinins  im  Harne  und  Untersuchungen  iiber 
Kreatininausscheidungen  im  Harne  der  Herbivoren.  Inaug.-Diss.,  Bern,  1910. 

c  Blatherwick,  Journ.  Biol.  Chem.,  1920,  42,  p.  517. 

d  Peters,  Biochem.  Journ.,  1920,  14,  p.  697. 

*  Palladin,  Arch.  f.  d.  ges.  Physiol.,  1924,  203,  p.  93;  ibid.,  204,  p.  150. 


106 


METABOLISM  OF  THE  FASTING  STEER 


last  day.  A  second  sheep,  weighing  58.4  kg.,  fasted  16  days  and  lost  13.6 
kg.  The  total  urinary  nitrogen  on  the  first  day  was  19.05  gm.  and  on  the 
last  day  6.17  gm.  Creatinine  was  excreted  during  the  entire  fast.  Creatine 
began  to  be  excreted  on  the  third  day  and  the  excretion  continued  through¬ 
out  the  fast.  The  nitrogen  excreted  per  kilogram  of  body-weight  per  24 
hours  was  0.326  gm.  at  the  beginning  and  0.138  gm.  at  the  end.  The 
creatinine  coefficient  fell  from  20.0  to  15.5  mg.  In  a  second  communication 
the  results  are  given  for  an  adult  sheep,  which  weighed  64  kg.  and  fasted 
8  days.  The  nitrogen  in  the  urine  on  the  first  day  was  9.43  gm.,  on  the 
second  day  10.42  gm.,  and  on  the  eighth  day  5.40  gm.  per  24  hours.  The 
author  believes  that  during  fasting  there  is  an  increase  in  the  formation  of 
acids  and  that  in  the  neutralization  of  these  acids  the  excretion  of  ammonia 
is  increased.  A  comparison  of  the  effect  of  an  acid  feed,  such  as  oats,  with 
an  alkaline  feed  following  the  fast  showed  a  greater  ammonia  excretion 
with  the  acid  feed. 

In  connection  with  a  study  of  the  metabolism  in  acetonemia,  Sjollema  and 
van  der  Zandea  determined  the  total  acetone  bodies,  ammonia  nitrogen, 
phosphoric  acid,  glucose,  and  calcium  in  the  urine  of  milch  cows.  On  three 
different  occasions  they  attempted  to  provoke  acetonemia  experimentally  by 
producing  glycosuria  with  injections  of  phlorizin  followed  by  fasting.  They 
found  that  during  the  days  of  the  injections  the  urine  contained  2.2  to  2.4 
per  cent  of  glucose,  but  no  acetone  bodies.  Ketonuria  occurred  only  when, 
after  some  days  of  phlorizin  glycosuria,  no  food  was  given  to  the  cows  for 
2  days.  The  quantity  of  acetone,  however,  was  much  lower  than  in  typical 
acetonemia,  about  0.4  gm.  in  1,000  c.  c.  They  conclude,  therefore,  that  the 
cow  does  not  easily  produce  much  acetone,  except  in  certain  diseased 
conditions. 

The  most  recent  contribution  to  this  study  of  the  urine  of  fasting  rumi¬ 
nants  is  that  of  Forbes,  Fries,  and  Kriss,* 6  who,  following  a  plan  of  Professor 
Armsby,  studied  cows  which  fasted  for  3,  6,  and  9  days.  Since  the  urine  and 
feces  were  not  separated  as  a  rule,  it  was  possible  to  study  the  urine  on  only 
a  few  days.  During  a  10-hour  period  at  the  end  of  the  fourth  fasting  day 
one  cow  voided  1.518  kg.  of  urine  containing  28  gm.  of  nitrogen.  During  the 
succeeding  24  hours  she  passed  1.804  kg.  of  urine  containing  26.5  gm.  of 
nitrogen.  Another  cow  on  the  sixth  fasting  day  voided  in  24  hours  1.978  kg. 
of  urine  with  a  nitrogen  content  of  28.2  gm.  At  the  end  of  71/2  days  she 
excreted  42.8  gm.  of  nitrogen  in  a  24-hour  period.  In  the  case  of  another  cow 
on  the  sixth  day  21.1  gm.  of  nitrogen  were  excreted  in  24  hours.  The  daily 
nitrogen  excretion  of  this  same  cow  during  the  sixth  to  the  ninth  day  of 
fasting  was  28.7  gm.  and  during  the  seventh  to  the  ninth  day  was  31.2  gm. 
The  difficulty  of  separating  the  urine  and  feces  of  cows  has  for  years  retarded 
the  study  of  the  urine  per  se  with  cows.  A  satisfactorily  functioning 
mechanical  device  (eliminating  the  use  of  a  harness  or  other  encumbrances) 
for  the  separation  of  the  urine  and  feces  of  cows  has  been  developed  at  the 
New  Hampshire  Agricultural  Experiment  Station  by  one  of  us  (E.  G.  R.) 
and  at  the  moment  of  writing  is  being  most  successfully  employed. 


“Sjollema  and  van  der  Zande,  Journ.  Metabolic  Research,  1923,  4,  p.  525. 

6  Forbes,  Fries,  and  Kriss,  Journ.  Dairy  Sci.,  1926,  9,  p.  15. 


URINE 


107 


Chemical  Methods 

Preservation  of  urine — The  necessity  of  transporting  the  urines  from  Dur¬ 
ham  to  Boston,  the  unavoidable  delay  in  the  analyses  at  the  Nutrition 
Laboratory,  and  the  lack  of  refrigeration  made  it  imperative  to  develop  a 
method  for  the  preservation  of  the  urines.  Willinger0  reports  that  the  urine 
of  12  large  ruminants  had  an  average  pa  of  8.70.  Since  this  would  predis¬ 
pose  towards  spoiling,  we  took  immediate  steps  to  have  the  urine  made 
acid.  Varying  amounts  of  concentrated  hydrochloric  acid  were  placed  in 
the  collection  bottles,  and  if,  in  spite  of  this,  it  was  found  at  the  time  of 
weighing  the  bottles  and  contents  that  the  urine  was  still  alkaline,  further 
acid  was  added  until  the  urine  reacted  acid.  We  have  evidence  that  decom¬ 
position  of  some  nitrogenous  substances  takes  place  rapidly  in  the  original 
urine,  even  in  the  presence  of  thymol  or  chloroform.  Undoubtedly  creatinine 
rapidly  disappears. 

Methods  of  analysis — To  the  collected  volume  of  urine  there  was  auto¬ 
matically  added  a  certain  amount  of  water  whenever  the  collection  was 
made  inside  the  respiration  chamber,  this  water  being  necessary  to  seal  the 
trap  in  the  urine  hose.  The  analyses  were  made  on  the  volumes  of  urines, 
and  consequently  it  was  necessary  to  calculate  the  volume  of  the  urine  plus 
the  water  and  hydrochloric  acid  added.  The  analyses  of  the  nitrogenous 
constituents  were  for  the  most  part  made  by  the  commonly  accepted  supe¬ 
rior  methods  of  Folin  and  his  associates,6  but  in  the  case  of  the  phenols,  for 
example,  Tisdall’s  modification  of  Folin’s  method  was  used.0 

Statistics  of  Results 

It  is  impossible  to  report  in  detail  in  this  monograph  the  results  of  all 
the  innumerable  analyses  carried  out  by  Dr.  Carpenter  and  his  associates, 
and  reference  must  be  made  for  such  details  to  the  extensive  discussion  of 
the  urines  of  these  fasting  steers  to  be  published  later.  In  the  fasts  of  steers 
C  and  D  up  to  and  including  those  in  November  1922,  the  chief  urinary 
constituents  determined  were  the  total  nitrogen  and  the  total  chlorides. 
The  data  for  these  determinations,  together  with  the  records  of  the  volumes 
of  urine  excreted,  have  been  summarized  in  Table  28.  In  the  fasts  of  steers 
C  and  D  in  November  1923  and  March  1924,  and  in  the  fasts  of  the  two 
younger  steers,  E  and  F,  in  February  1924,  much  more  extensive  urine 
analyses  were  carried  out.  The  study  of  the  total  nitrogen  has  long  been 
considered  an  important  one,  but  this  study  has  now  been  surpassed,  thanks 
to  the  researches  of  Folin,  by  an  interest  in  the  partition  of  the  nitrogen. 
The  analyses  of  the  urines  during  these  later  fasts  therefore  included  the 
partition  of  the  nitrogen  according  to  modern  methods,  and  the  results  have 
been  recorded  in  Table  29.  Since  it  was  necessary  to  preserve  the  urines  in 
these  later  fasts  with  hydrochloric  acid,  no  determinations  of  the  chlorides 
were  made,  but  determinations  were  made  of  the  total  nitrogen,  urea- 
nitrogen,  ammonia-nitrogen,  amino-acid  nitrogen,  hippuric-acid  nitrogen, 
and  preformed  and  total  creatinine,  the  data  for  all  of  which  are  given  in 

0  Willinger,  Arch.  f.  d.  ges.  Physiol.,  1924,  202,  p.  468. 

b  Folin,  Laboratory  manual  of  biological  chemistry,  New  York,  1922. 

*  Tisdall,  Journ.  Biol.  Chem.,  1920,  44,  p.  409. 


108 


METABOLISM  OF  THE  FASTING  STEER 


Table  28. — Volume  of  urine  and  total  nitrogen  and  chlorides  in  urines  of  steers  C  and  D  from 

December  1921  through  November  1922 


Date  and  steer 


1921 

Steer  C: 

Nov.  26  to  Dec.  6. 


Dec. 

Dec. 

Dec. 

Dec. 

Dec. 

Dec. 


6-  7. 

7-  8. 

8-  9. 

9- 10. 
10-11. 
11-12. 


Dec.  12-13. 


Dec.  13  to  Dec.  22. . . . 
Steer  D: 

Nov.  26  to  Dec.  6 . 


Dec. 

Dec. 

Dec. 

Dec. 


6-  7. 

7-  8. 

8-  9. 

9- 10. 


Dec.  10-11. 
Dec.  11-12. 
Dec.  12-13. 


Dec.  13  to  Dec.  22.  . . . 
Steer  C: 

Dec.  22,  1921,  to  Jan.  4, 
1922 . 

1922 

Jan.  4-  5 . 

Jan.  5-  6 . 

Jan.  6-  7 . 

Jan.  7-  8 . 

Jan.  8-  9 . 

Jan.  9-10 . 

Jan.  10-11 . 

Jan.  11-12 . 

Jan.  12-13 . 

Jan.  13-14 . 

Jan.  14  to  Feb.  2 . 

Steer  D: 

Dec.  22,  1921,  to  Jan. 
4,  1922 

Jan.  4-  5 . 

Jan.  5—  6 . 

Jan.  6—  7 . 

Jan.  7-  8 . 

Jan.  8—  9 . 

Jan.  9-10 . 

Jan.  10-11 . 

Jan.  11-12 . 

Jan.  12—13 . 

Jan.  13-14 . 

Jan.  14  to  Feb.  2 . 


Dura¬ 

tion 

of 

period 


hrs. 

10  days 

24 

22 

26 

18 

24 

28 

18 

9  days 

10  days 

24 

24 

24 

25 
3  16 

25 

25 

9  days 
13  days 


24 

24 

24 

16 

29 

28 

21 

27 

18 

27 

18  days 
13  days 

24 

23 
26 

24 
23 
22 

28 
23 
22 
26 

19  days 


Volume  of  urine 


Total 


liters 

145.74 


6.46 

3.40 

3.10 

1.91 

2.91 
2.60 
1.62 


132.28 

‘44.17 


8.43 
2.87 
1.42 
5.46 
3 1.79 
1.40 
4.94 


‘33.99 

‘67.46 


9.21 
4.30 

3.21 
1.62 
2.25 

4.54 
2.07 
1.60 

1.55 
1.80 


66.61 


67.75 


12.84 

3.46 

4.42 

3.10 

3.11 
3.00 
4.25 
1.83 
1.32 

2.43 


‘75.12 


Per 

hour 


c.  c. 
5 191 


269 

157 

117 

103 

122 

93 

91 


*149 
3 184 


351 

121 

60 

223 

112 

57 

200 


157 


!  216 


384 

179 

134 

103 

78 

165 

98 

59 

86 

67 


!  154 


2  217 


535 

150 

173 

129 

138 

139 
152 

80 

61 

93 


3 165 


Total  nitrogen 


For 

period 


gm. 

594 


64.7 
60.0 

81.5 
42.3 

50.8 

55.5 
42.7 


280 

575 


49.3 
50.7 

48.3 
61.2 

3  32. 7 
53.1 
50.7 


210 


1242 


123 

118 

89.8 

44.2 

66.9 

62.3 
37.1 

43.6 

30.4 

44.7 


802 


1320 


122 

89.9 
85.4 
66.8 
57.0 

49.9 

55.7 

37.8 
32.2 
35.6 


905 


Per 

hour 


gm. 

2.48 


2.70 

2.77 

3.08 

2.29 

2.13 

1.98 

2.41 


1.30 


2.40 


2.05 

2.13 
2.03 
2.50 
2.05 

2.14 
2.06 


.97 


3.98 


5.15 

4.91 

3.74 

2,81 

2.31 

2.27 

1.77 

1.61 

1.68 

1.66 


1.86 


4.23 


5.07 

3.91 

3.35 

2.78 

2.53 

2.32 

1.99 

1.64 

1.50 

1.37 


1.99 


Chlorides  (NaCl) 


For 

period 


gm. 


29.0 

5.56 

1.82 

1.06 

1.42 

1.46 

.823 


34.0 

8.77 

.290 


.305 

.820 


42.9 

10.5 

2.58 

.727 

1.67 

4.60 

3.39 

.900 

1.75 

2.28 


48.7 

16.7 
4.26 


1.17 


Per 

hour 


gm. 


1.21 

.257 

.069 

.057 

.060 

.052 

.046 


1.42 

.369 

.012 


.012 

.033 


1.79 

.438 

.108 

.046 

.058 

.167 

.162 

.033 

.097 

.084 


2.03 

.728 

.167 


.045 


1  Kilograms. 


2  Grams. 


3  Urine  for  the  period  2  p.  m.  to  7h31m  p.  m.  Dec.  10  was  lost. 


URINE 


109 


Table  28. — Volume  of  urine  and  total  nitrogen  and  chlorides  in  urines  of  steers  C  and  D  from 
December  1921  through  November  1922 — Continued 


Date  and  steer 

Dura¬ 

tion 

of 

period 

Volume  of  urine 

Total  nitrogen 

Chlorides  (NaCl) 

Total 

Per 

hour 

For 

period 

Per 

hour 

For 

period 

Per 

hour 

1922 

hrs. 

liters 

c.  c. 

gm. 

gm. 

gm. 

gm. 

Steer  C: 

Mar.  31  to  Apr.  17. . . . 

17  days 

‘68.11 

3 167 

1229 

3.01 

Apr.  17-18 . 

24 

5.18 

216 

78.2 

3.26 

55.4 

2.31 

Apr.  18-19 . 

21 

7.63 

363 

75.2 

3.58 

13.7 

.655 

Apr.  19-20 . 

24 

5.21 

217 

67.8 

2.83 

Apr.  20-21 . 

24 

3.10 

129 

78.6 

3.28 

Apr.  21-22 . 

24 

1.97 

82 

57.9 

2.41 

1.72 

.072 

Apr.  22-23 . 

27 

3.78 

140 

63.9 

2.37 

1.19 

.044 

Apr.  23-24 . 

21 

2.13 

101 

42.9 

2.03 

.926 

.044 

Apr.  24—25 . 

24 

1.87 

77 

48.8 

2.00 

.972 

.040 

Apr.  25-26 . 

24 

2.03 

86 

52.3 

2.23 

.563 

.024 

Apr.  26-27 . 

21 

2.07 

101 

34.3 

1.67 

1.06 

.052 

Apr.  27-28 . 

30 

4.57 

151 

51.9 

1.71 

5.42 

.179 

Apr.  28-29 . 

22 

1.97 

90 

36.3 

1.65 

2.01 

.092 

Apr.  29-30.  .  . . 

20 

1.57 

78 

39.7 

1.99 

1.45 

.073 

Apr.  30-May  1 . 

30 

2.31 

77 

47.2 

1.57 

2.61 

.087 

May  1  to  May  9 . 

8  days 

‘19.30 

3 101 

222 

1.16 

Steer  D: 

Mar.  31  to  Apr.  17. . . . 

17  days 

‘74.95 

3 184 

1304 

3.20 

Apr.  17—18 . 

24 

5.54 

231 

91.1 

3.80 

53.6 

2.23 

Apr.  18-19 . 

24 

6.64 

273 

88.9 

3.65 

19.0 

.779 

Apr.  19-20 . 

22 

6.94 

322 

78.7 

3.65 

7.52 

.349 

Apr.  20-21 . 

25 

3.14 

124 

71.1 

2.80 

.927 

.037 

Apr.  21-22 . 

25 

2.38 

97 

62.3 

2.53 

1.47 

.060 

Apr.  22-23 . 

24 

2.23 

92 

56.5 

2.33 

1.48 

.061 

Apr.  23-24 . 

24 

1.54 

65 

38.9 

1.66 

.621 

.026 

Apr.  24-25 . 

25 

1.82 

74 

44.0 

1.80 

Apr.  2*>—2fi .  .  ,  . 

24 

1  89 

80 

38.3 

1.63 

Apr.  26-27 . 

25 

7.63 

305 

45.1 

1.80 

6.90 

.276 

Apr.  27-28 . 

24 

2.28 

96 

35.0 

1.48 

4.65 

.196 

Apr.  28-29 . 

24 

3.76 

155 

37.3 

1.54 

6.67 

.275 

Apr.  29-30 . 

23 

5.63 

242 

35.8 

1.54 

7.11 

.305 

Apr.  30-May  1 . 

22 

1.87 

85 

33.9 

1.54 

2.12 

.096 

May  1  to  May  9 . 

8  days 

‘22.40 

3 117 

208 

1.08 

Steer  C : 

May  9  to  June  1 . 

23  days 

‘103.39 

3 187 

1839 

3.33 

572 

1.04 

June  1-  2 . 

24 

6.91 

288 

100 

4.19 

39.3 

1.64 

June  2-  3 . 

24 

9.76 

407 

103 

4.30 

50.3 

2.10 

June  3-  4 . 

23 

4.00 

176 

80.5 

3.57 

11.1 

.492 

June  4-  5 . 

23 

2.45 

105 

62.0 

2.67 

3.09 

.133 

June  5—  6 . 

24 

2.98 

125 

60.8 

2.54 

4.00 

.167 

1  Kilograms. 


3  Grams. 


110 


METABOLISM  OF  THE  FASTING  STEER 


Table  28. — Volume  of  urine  and  total  nitrogen  and  chlorides  in  urines  of  steers  C  and  D  from 
December  1921  through  November  1922 — Continued 


Date  and  steer 

Dura¬ 

tion 

of 

period 

Volume  of  urine 

Total  nitrogen 

Chlorides  (NaCl) 

Total 

Per 

hour 

For 

period 

Per 

hour 

For 

period 

Per 

hour 

1922 

hrs. 

liters 

c.  c. 

gm. 

gm. 

gm. 

gm. 

Steer  D: 

May  9  to  June  1 . 

23  days 

*101.22 

2 183 

1902 

3.45 

599 

1.09 

June  1-  2 . 

23 

6.70 

291 

93.8 

4.08 

73.1 

3.18 

June  2—  3 . 

24 

3.90 

159 

96.2 

3.93 

June  3—  4 . 

24 

8.78 

363 

88.1 

3.64 

June  4-  5 . 

24 

2.90 

122 

66.1 

2.77 

1.87 

.078 

June  5—  6 . 

23 

7.28 

317 

62.9 

2.73 

Steer  C: 

Nov.  6—  7 . 

22 

8  5.79 

8  263 

8  99.0 

8  4. 50 

Nov.  7-  8 . 

26 

3.42 

133 

100.6 

3.92 

Nov.  8-  9 . 

18 

1.76 

99 

59.4 

3.35 

Nov.  9—10 . 

30 

2.88 

97 

94.5 

3.19 

Nov.  10—11 . . 

25 

2.79 

112 

80.0 

3.21 

Nov.  11—12 . 

16 

1.86 

119 

49.3 

3.16 

Nov.  12-13 . 

25 

2.57 

104 

73.4 

2.97 

Nov.  13-14 . 

24 

2.55 

105 

66.5 

2.74 

Nov.  14—15 . 

29 

2.58 

89 

72.0 

2.4S 

Steer  D: 

Nov.  6—  7 . 

22 

6.06 

276 

99.4 

4.52 

Nov.  7-  8 . 

20 

2.82 

139 

91.6 

4.51 

Nov.  8-  9 . 

28 

2.72 

97 

93.3 

3.34 

Nov.  9—10 . 

25 

3.21 

127 

80  0 

3.18 

Nov.  10—11 . 

24 

5  58 

237 

86  0 

3.65 

Nov.  11-12 . 

25 

3.84 

155 

71.3 

2.88 

Nov.  12-13 . 

17 

<1.84 

4  109 

4  47.8 

4  2.84 

Nov.  13-14 . 

24 

1.94 

81 

54.5 

2.28 

1  Kilogram.  2  Grams.  8  Some  urine  was  spilled. 

4  Approximately  200  grams  of  urine  were  lost. 


Table  29.  In  practically  all  of  the  fasts  other  urinary  constituents  were 
also  determined,  such  as  inorganic  sulphate,  ethereal  sulphate,  neutral  sul¬ 
phur,  and  total  sulphur,  the  free  and  conjugated  phenols,  acetone  and  dia- 
cetic  acid  (determined  together),  /?-oxybutyric  acid,  total  fixed  bases,  and 
the  organic  acids,  but  reference  must  be  made  to  Carpenter’s  report  for 
these  details. 

The  ever-present  complexity  of  irregularity  in  the  voiding  of  urine  and 
the  high  probability  of  the  incomplete  emptying  of  the  bladder,  particularly 
at  the  end  of  the  period  of  collection,  make  the  study  of  the  urinary  output 
and  its  constituents  on  any  time  basis  always  somewhat  approximate. 
Because  of  the  inability  to  secure  sharply  divided  24-hour  periods,  the 
record  of  the  exact  time  of  each  urination  became  important,  and  this  was 
usually  noted  carefully  in  the  later  fasts.  In  the  earlier  fasts  the  lack  of 
enough  assistants  made  such  records  somewhat  uncertain,  although  they 
were  kept.  In  general,  however,  each  period  of  collection  represents  not 
far  from  a  24-hour  day.  In  the  fasts  recorded  in  Table  28  the  periods  of 
collection  have  been  recorded  to  the  nearest  hour,  as  they  were  all  approxi- 


URINE 


111 


Table  29. — Amounts  per  hour  of  nitrogen  constituents  determined  in  urines  of  fasting  steers — Continued 


METABOLISM  OF  THE  FASTING  STEER 


Total 

creatinine 

si  •  • 

«OO^NNhnhO)CO«COcOONOO 

OiNNCDcDcOCDiOOiOiOCONCDCOiOcDcD 

©  rH 

05NHHC0  05 

O  05  CO  N  CO 

Preformed 

creatinine 

s  :  : 

.  . 

OOtOOOiOfflrfnNUJN'rldOttCNOO 

ONONN(OiOiOOcD10®NOiOiOOffl 

O  rH 

CO  00  00  W  N 

05  lO  00  O  N  O 

Hippuric- 

acid 

nitrogen 

gm. 

0.318 

■hMNOMrfe)U5«MIN»N(NN  •  M 
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CO  (M  CO  CO  >0  H 

^  CO  00  00  CO  N 

O  O  O  O  rH  rH 

Amino- 

acid 

nitrogen 

gm. 

0.224 

«(MOiN^OCOOONOtOHCO(NiOO)CO(N 

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nitrogen 

s  :  : 

.  . 

H^SONHWCDCONHOO^iOiCCONOJ 

02C0^(MC0^C0>0(NOC0NOOOC0ON 

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© 

05  O  00  H  o  CO 

C0  0rt<050i0 

rH  ^0  rH  <0  rH 

Urea- 

nitrogen 

1  ^  : 

Ca  .  . 

HNMHHNOOHCOCOH^NOO>OiO^ 

•^C0C5N05l>a500C0(MHOH(NHHCSH 

O  rH  iH  rH  iH  rH  rH  rH  rH  rH  ^H 

h  oi  CO  00  GO  H 
^  CO  05  rt<  ^  rf 

rH 

Total 

nitrogen 

gm. 

0.93 

1.18 

^as^ONCOWOOO^COOiOCOOiOCOG 

C^OCOC^iOCONCONOOOONOOOCiONiO 

rHiHrHrHiHrHrHrHC^rHrHiHrHrHiHrHrHrH 

*0  Tjc  »0  <N  00  t>* 

N  H  GO  O  CO  O 

M  H  H  H  H  H 

Volume 

of 

urine 

^  CD  05 
.  *0 
*■5  r—i  rH 

cooMN^coioeowiowNcocoooow^ 

O00^C0N^N05O0)00CDiO^HGC0300 

H  H  T}1  rH  rH  rH  rH 

NCOW05005 

O  CO  O  lO  Ol  lO 

CM  rH  H  <M 

Duration 

of 

period 

.8 

SmiO  lOHONOOHOONNOMOOiOiONiOOOO  SNHHOM 

S  >>  rt<(MiO  rHC0C'5<NTtl<N''}<<NrH  -4*  CO  iO  N  M  «3  h 

OQ 

.  "O 

=o  ^0  HiOQOiOOMOMNONCONNCOCO^O  CO  05  O  CO 

rH  1-Hi-Hi-HrHrH  rH  rH  rH  rH  rH  iH  rH 

Date  and  steer 

1924 

Steer  D: 

Feb.  27-Mar.  2 . 

Mar.  2-  3 . 

Mar.  3 . 

Mar.  3-  4 . 

Mar.  4 . 

Mar.  4-  5 . 

Mar.  5 . 

Mar.  5-  6 . 

Mar.  6 . 

Mar.  6-  7 . 

Mar.  7 . 

Mar.  7-  8 . 

Mar.  8 . 

Mar.  8-  9 . 

Mar.  9 . 

Mar.  9-10 . 

Mar.  10 . 

Mar.  10-11 . 

Mar.  11 . 

Mar.  11-12 . . 

Mar.  12 . 

Mar.  12-13 . 

Mar.  13 . 

Mar.  13-14 . 

Mar.  14 . 

Mar.  14-15 . 

URINE 


113 


.  •  CO  CO 

^©OOOMiO^iOiOCONO 

N  GO  ©  h  O  O  -ICO 

h  •H^^QOGOOOCOOOCO^ 

n*  io  co  03 

8  •  H  CC 

0<)C^COfOt^'^4-^44O4O^Tt4rJ4t)4 

•  <N  eo 

CO  -^^CO^^iOiOiOiO^^ 

CD  Tfi  CO  03 

^  -o  ' 

; 

.  •  r- 

g  'OH 

s  :<b 

N  O  iO  N  M  CO  GO  'O  O  CO  iO  N  ^ 
H1N<NC^CSCIC0C0WNC1(N 

Tt^  o  TjH  00  t>  •  O  CO 

IO  H  cq  (N  Cl  (M  •  03  03 

lO  '^oOOOO^MMCOOh 
(M  *COCO<NTt<COCOCOeOCOCOCO 

^ooo 

Tt<  ^  CO  03 

am. 

0.035 

.063 

CO  *D  C5  t>*  IO  •  •  ‘I-OOIOO 

O  05  «C  Tt<  ©  (N  •  •  •  03  H  03  03 

OOOOOO  •  •  •  O  O  O  O 

•  CO  CO  CO  -co  • 

•  o:  CO  (M  N  ^  -co  • 

■  (O  rH  i-H  r-H  i-H  •  i-H  • 

.140 

.048 

.026 

.022 

.019 

.018 

•  r>  ^  co 

•COHO 

•  O  rH  rH 

am. 

0.093 

.168 

HOHioiooooHMMiflnoi 

IHOMHOtOOHMHMHH 

OOOOOOOOOOOOO 

^  CO  ^  GO  H  ■  C5  03 

HrftCOCOlOO  •  H  s 

OOOOOO  •  i-H  o 

b-  •  CO  05  i—4  •  oo  lO  h  1C  S  o  o 

tH  ■  O  i-H  (N  -00t-40000 

o  -ooo  -ooooooo 

M  iH  JO  O 

H  rt  N  N 

O  O  O  O 

am. 

0.236 

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114 


METABOLISM  OF  THE  FASTING  STEER 


mately  24  hours  long.  Hence  the  total  daily  amounts  are  reasonably  com¬ 
parable  from  day  to  day.  The  large  differences  in  the  time  intervals  occa¬ 
sionally  found  must,  however,  always  be  held  in  mind  in  making  any  final 
deductions.  In  the  fasts  in  November  1923,  recorded  in  Table  29,  the 
24-hour  period  of  collection  was  likewise  adhered  to  reasonably  closely.  In 
the  1924  fasts  the  collections  were  made  more  frequently,  and  in  Table  29, 
therefore,  the  length  of  each  period  is  given  in  hours  and  minutes. 

Since  it  was  impossible  in  these  fasts  to  secure  sharply  divided  24-hour 
or  12-hour  periods,  it  has  seemed  best  to  discuss  the  chemistry  of  the  urine 
in  all  of  the  different  fasts  on  the  basis  of  the  amounts  per  hour.  Aside  from 
the  total  excretion  of  nitrogen,  which  is  of  chief  interest  in  connection  with 
the  protein  loss,  the  chemical  analysis  of  the  urine  is  of  the  greatest  value 
in  indicating  the  proportions  of  the  various  ingredients  excreted  and  the 
changes  in  these  relationships  as  the  fasts  progressed.  Hence  in  practically 
all  cases  the  expression  of  the  results  on  the  per  hour  basis  is  reasonably 
satisfactory.  Logically  there  is  no  reason  for  adhering  to  the  24-hour 
period,  since  fasting  brings  about  a  change  in  the  metabolic  level  which 
takes  place  from  hour  to  hour  as  well  as  from  24  hours  to  24  hours.  Hence 
the  hourly  values  reported  in  Table  29  for  the  later  fasts  present  a  much 
more  intelligent  picture  of  the  course  of  the  excretion  of  the  different  urinary 
constituents. 

In  addition  to  the  study  of  the  urine  during  the  fasting  periods  proper, 
analyses  were  also  made  during  the  feed  periods  preceding  and  following  the 
fasts.  The  data  for  these  feed  periods  are  likewise  recorded  in  Tables  28 
and  29,  being  separated  from  the  fasting  data  by  horizontal  lines.  In 
Table  28  the  total  volume  of  urine  during  these  feed  periods  is  given  in 
kilograms  instead  of  in  liters,  and  the  volume  of  urine  per  hour  is  given  in 
grams  instead  of  in  cubic  centimeters,  as  indicated  at  the  head  of  the 
columns  in  the  table. 

One  must  realize,  in  analyzing  these  data,  that  the  fasts  in  November 
followed  pasture  feeding  and  that  prior  to  all  the  other  fasts,  with  the 
exception  of  those  in  February  and  March  1924,  the  steers  had  been  receiv¬ 
ing  an  approximately  maintenance  ration  of  hay  and  meal.  In  the  1924 
fasts  all  four  steers  had  been  for  a  considerable  period  of  time  on  a  low 
nutritive  plane. 

Discussion  of  Results 

CHLORIDES  IN  URINE 

In  the  first  few  fasts  of  steers  C  and  D,  information  was  secured  regarding 
the  chlorides  in  urine,  as  shown  in  Table  28.  Since  the  chloride  excretion 
is  dependent  in  large  part  upon  the  intake,  the  rapid  fall  noted  in  this 
excretion  during  the  fasting  periods  is  not  surprising.  The  excretion  drops 
off  enormously,  until  the  hourly  values  become  as  low,  in  one  instance,  as 
13  mg.  Owing  to  the  necessity  for  using  hydrochloric  acid  to  preserve  the 
urines,  it  was,  unfortunately,  impossible  to  study  the  chloride  excretion 
during  the  fasts  at  the  submaintenance  level. 


URINE 


115 


NITROGEN  EXCRETED  IN  URINE  PER  HOUR 

Nitrogen  is  the  most  characteristic  chemical  element  in  urine  and  for 
decades  has  been  considered  to  be  an  essential  index  of  protein  metabolism. 
The  nitrogen  excretion  per  hour  is  recorded  in  both  Table  28  and  Table  29. 
The  probable  24-hour  excretion  will  be  considered  subsequently  (see  pp. 
127  to  129)  in  connection  with  the  discussion  of  the  daily  loss  of  nitrogen 
both  in  the  urine  and  in  the  feces,  but  the  hourly  rate  of  excretion  is  of 
immediate  importance. 

Prior  to  the  fasts  the  hourly  excretion  of  nitrogen  by  steers  C  and  D  is 
not  far  from  2.5  to  4.5  grams,  except  prior  to  the  fasts  in  March  1924,  at 
the  submaintenance  level,  when  the  hourly  output  is  much  lower.  Similarly, 
with  steers  E  and  F  the  influence  not  only  of  submaintenance  feeding  but 
of  smaller  body-weights  results  in  a  low  hourly  output,  even  prior  to  the 
fast.  The  important  influence  of  the  preceding  ration  upon  the  hourly 
nitrogen  excretion  is  shown  in  the  fasts  in  March  1924  with  steers  C  and  D, 
when  the  body- weights  at  the  beginning  of  the  fasts  were  about  600  kg.  As 
a  matter  of  fact,  the  body-weights  were  the  third  highest  in  the  long  series 
of  fasts  with  these  two  animals,  and  yet  the  nitrogen  per  hour  is  lower  in 
this  fast  than  in  any  of  the  preceding  fasts.  Following  submaintenance 
feeding,  there  is  a  gradual  increase  in  the  nitrogen  excretion  in  the  first  four 
days  of  fasting,  but  in  the  fasts  following  maintenance  feeding  the  nitrogen 
has  a  tendency  to  fall  off  as  the  fast  progresses.  The  minimum  values  with 
both  animals  are  found,  as  is  to  be  expected,  in  the  fasts  at  the  submain¬ 
tenance  level,  when  the  excretions  of  both  steers  settle  down  to  approxi¬ 
mately  1.6  and  1.8  grams  per  hour.  This  corresponds  to  not  far  from  40 
grams  per  24  hours.  If  the  urinary  nitrogen  excretion  of  a  man  weighing 
approximately  60  kg.,  or  one-tenth  of  what  these  steers  weighed,  is  assumed 
to  be  one-tenth  of  the  minimum  nitrogen  excretion  noted  with  these  steers, 
it  would  be  about  4.0  grams.  This  is  about  as  low  a  value  as  has  ever  been 
found  with  man,  except  for  the  values  obtained  by  Petren“  with  his  diabetic 
patients  on  a  diet  high  in  fat  and  low  in  protein.  The  taking  of  food  fol¬ 
lowing  these  fasting  experiments  almost  invariably  lowered  the  nitrogen 
output  even  below  that  of  the  last  day  of  the  fast,  due  in  all  probability  to 
the  storage  of  nitrogen  to  replenish  the  loss  and  to  the  protective  action  of 
the  carbohydrate. 

That  the  excretion  of  nitrogen  was  essentially  independent  of  the  volume 
of  urine  is  brought  out  by  the  comparison  of  the  volume  of  urine  excreted 
per  hour  and  the  actual  nitrogen  output.  A  typical  instance  is  the  com¬ 
parison  for  steer  C  in  the  fast  in  January  1922.  On  the  fifth  day,  January 
8-9,  the  volume  was  78  c.  c.  per  hour  and  on  the  next  day  it  was  more  than 
double,  i.  e.,  165  c.  c.,  but  the  nitrogen  output,  on  the  contrary,  decreased 
from  2.31  to  2.27  gm.  per  hour.  In  most  of  the  fasts  the  nitrogen  excretion 
either  remains  at  a  fairly  constant  level  or  gradually  decreases,  irrespective 
of  the  volume  of  urine,  and  thus  there  is  not  a  “washing-out”  effect  of  previ¬ 
ously  metabolized  nitrogenous  products.  Even  on  the  low  metabolic  plane 
in  the  March  fasts  great  variations  in  the  volume  of  urine  are  found  with  a 

°  Petr6n,  Proc.  XI  Internat.  Physiol.  Congress,  Edinburgh,  1923;  ibid.,  Diabetes-Studier, 
Copenhagen,  1923,  p.  545. 


116 


METABOLISM  OF  THE  FASTING  STEER 


fairly  constant  level  of  nitrogen  excretion,  a  greater  irregularity  being  noted 
with  steer  D  than  with  steer  C.  With  steers  E  and  F,  an-  indication  of  a 
relationship  between  the  volume  of  urine  and  the  nitrogen  excretion  is  fre¬ 
quently  found.  For  example,  on  February  14  the  volume  of  urine  excreted 
by  steer  E  per  hour  is  642  c.  c.  and  the  nitrogen  per  hour  is  1.80  gm.  The 
period  is,  to  be  sure,  short.  During  the  next  period  of  14  hours  and  4  minutes 
the  volume  per  hour  is  only  46  c.  c.  and  the  nitrogen  output  is  0.84  gm.,  or 
one-half  that  of  the  preceding  period.  There  is,  in  this  instance,  a  decrease 
in  both  factors,  but  in  no  sense  a  strict  relationship  between  the  two. 

From  this  experience  and  from  that  of  Forbes,  Fries,  and  Kriss,°  one 
might  suggest  that  when  it  is  desirable  to  study  the  periodic  variations  in 
the  nitrogen  output  after  the  ingestion  of  food  or  the  hourly  variations  in 
the  urine  even  during  fasting,  preliminary  experiments  with  animals  should 
be  made  and  an  animal  selected  which  shows  regularity  in  nitrogen  excretion. 
It  is  evident  in  our  series  of  fasts,  for  example,  that  steer  C  is  extraordinarily 
regular  in  the  voiding  of  the  nitrogen  constituents,  irrespective  of  the  quan¬ 
tity  of  the  urine.  One  might  infer  that  at  each  voiding  the  bladder  was 
reasonably  well  emptied  and  that  physiologically  the  animal  functioned 
regularly.  Steer  F  was  likewise  regular,  but  steers  D  and  E  show  con¬ 
siderable  variability  in  the  excretion  of  the  urinary  constituents.  Further 
consideration  of  the  nitrogen  output  may  best  be  made  when  the  apportion¬ 
ment  of  the  nitrogen  among  its  various  constituents  is  studied. 

PARTITION  OF  TJRINARY  NITROGEN 

In  the  fasts  of  steers  C  and  D  in  November  1923,  the  combined  urea- 
nitrogen  and  ammonia-nitrogen  decreases  as  the  fast  progresses.  (See 
Table  29.)  A  striking  fall  in  the  amino-acid  nitrogen  and  the  hippuric-acid 
nitrogen  was  observed,  particularly  after  the  first  day.  The  results  for  the 
preformed  and  total  creatinine  are  hardly  interpretable  without  reference 
to  the  total  nitrogen  excretion  on  the  same  day,  but  they  both  remain  high, 
with  little  indication  of  a  falling  off.  In  the  fasts  in  March  1924,  at  the 
submaintenance  level,  the  urea-nitrogen  and  the  ammonia-nitrogen  are 
separated  for  the  first  time,  and  it  is  clear  from  these  results  that  there  is  a 
distinct  tendency  for  the  urea-nitrogen  to  increase  and  for  the  ammonia- 
nitrogen  to  remain  essentially  constant  after  the  first  two  or  three  days. 

The  amino-acid  nitrogen  in  the  case  of  steer  C  drops  off  markedly  during 
fasting,  as  does  the  hippuric-acid  nitrogen,  but  the  preformed  and  total 
creatinine  remain  fairly  constant.  After  the  fast,  when  food  is  given,  little 
change  takes  place  except  that  the  urea-nitrogen  decreases  somewhat  and 
the  ammonia-nitrogen  increases.  With  steer  D  the  picture  is  not  unlike 
that  with  steer  C,  namely,  a  rise  in  the  urea-nitrogen,  a  tendency  for  a 
slight  increase  in  the  ammonia-nitrogen,  a  rapid  decrease  in  the  amino-acid 
and  the  hippuric-acid  nitrogen,  and  essential  constancy  in  the  creatinine. 
With  refeeding  there  is  a  striking  fall  in  the  urea-nitrogen  of  steer  D.  The 
ammonia-nitrogen  tends  to  remain  about  constant  and  the  amounts  of 
amino-acid  and  hippuric-acid  nitrogen  tend  to  increase.  There  is  no  strik¬ 
ing  change  in  the  creatinine. 

°  Forbes,  Fries,  and  Kriss,  Journ.  Dairy  Sci.,  1926,  9,  p.  15. 


URINE 


117 


Table  30. — Partition  of  nitrogen  excreted  in  unnes  of  fasting  steers 


Proportion  of  total  nitrogen  in — 

Date  and  steer 

Urea 

Am¬ 

monia 

Amino 

acids 

Hip- 

puric 

acid 

Pre¬ 

formed 

creati¬ 

nine 

Total 

creati¬ 

nine 

Steer  C:  1923 

p.  ct. 

p.  ct. 

p.  ct. 

p.  ct. 

p.  ct. 

p.  ct. 

Nov.  5-  6 . 

75 

.9 

1.0 

3.7 

5.4 

8.1 

Nov.  6-  7 . 

77 

.9 

.5 

2.2 

5.2 

9.2 

Nov.  7-  8 . 

82 

.7 

.4 

1.4 

6.5 

11.2 

Nov.  8-  9 . 

81 

.0 

.4 

1.3 

8.3 

10.5 

Nov.  9-10 . 

74 

.1 

.6 

1.5 

9.3 

10.8 

Steer  D: 

Nov.  5-  6 . 

78.9 

2.0 

3.4 

5.9 

8.4 

Nov.  6-  7 . 

82 

.2 

.3 

2.0 

7.1 

10.3 

Nov.  7—  8 . 

65 

.7 

.4 

1.6 

7.4 

10.9 

Nov.  8-  9 . 

74 

.1 

.3 

1.3 

8.7 

10.3 

Nov.  9-10 . 

74 

.7 

.3 

1.8 

7.9 

9.7 

Steer  C:  1924 

Mar.  2—  3 . 

38 

.3 

17.8 

27.5 

18.0 

20.0 

Mar.  3 . 

26.4 

6.7 

6.0 

22.9 

23.8 

Mar.  3-  4 . 

40.1 

2.1 

3.0 

8.9 

25.3 

27.7 

Mar.  4 . 

29.1 

2.2 

2.5 

9.5 

20.0 

20.2 

Mar.  4-5 . 

58.4 

1.1 

1.1 

6.3 

14.7 

16.8 

Mar.  5 . 

1  51 . 6 

>4.6 

1  1.5 

1  12.9 

1 17 . 6 

Mar.  5 . 

63.6 

3.2 

1.2 

3.6 

13.8 

17.6 

Mar.  5-6 . 

58.7 

1.6 

.7 

2.3 

13.4 

18.3 

Mar.  6-7 . 

64.7 

2.0 

.8 

1.9 

12.6 

18.0 

Mar.  7 . 

62.4 

3.7 

.5 

1.8 

13.0 

14.8 

Mar.  7-8 . 

67.0 

2.8 

.6 

1.8 

12.9 

13.7 

Mar.  8-9 . 

68.6 

2.6 

.5 

1.6 

12.6 

13.1 

Mar.  9 . 

66.2 

3.5 

.5 

1.7 

13.5 

13.8 

Mar.  9-10 . 

71.1 

2.9 

.7 

1.7 

13.6 

13.3 

Mar.  10 . 

69.3 

3.7 

.7 

1.6 

13.5 

13.1 

Mar.  10-11 . 

66.9 

3.4 

.7 

1.7 

13.5 

13.3 

Mar.  11 . 

70.0 

3.9 

.7 

14.5 

14.3 

Mar.  11-12 . 

75.5 

2.0 

.7 

1.7 

15.0 

15.1 

Mar.  12-13 . 

70.1 

3.7 

.6 

1.7 

14.6 

15.5 

Mar.  13-14 . 

66.0 

5.0 

.9 

2.5 

15.1 

16.1 

Mar.  14 . 

59.2 

6.5 

1.2 

16.0 

16.2 

Mar.  14-15 . 

61.1 

5.8 

1.1 

6.2 

13.6 

14.7 

Steer  D:  1924 

Mar.  2-3 . 

34 

.7 

18.9 

26.8 

Mar.  3 . 

33.2 

7.3 

3.5 

26.9 

27.7 

Mar.  3-4 . 

34.3 

3.1 

2.9 

16.1 

23.8 

24.0 

Mar.  4 . 

68.4 

3.5 

1.4 

10.3 

18.3 

19.5 

Mar.  4-5 . 

54.7 

1.5 

1.0 

5.6 

20.1 

18.5 

Mar.  5 . 

59.9 

2.5 

.9 

4.3 

17.2 

16.3 

Mar.  5-6 . 

57.0 

3.0 

.7 

2.9 

17.8 

17.0 

Mar.  6 . 

57.0 

7.7 

.7 

2.6 

12.2 

13.2 

Mar.  6-7 . 

61.9 

4.3 

.6 

2.2 

15.3 

14.7 

Mar.  7 . 

58.8 

4.4 

.6 

1.9 

13.8 

13.6 

Mar.  7-8 . 

67.6 

5.9 

.5 

1.8 

13.7 

12.1 

Mar.  8 . 

59.5 

7.0 

.8 

1.8 

13.0 

11.3 

Mar.  8-9 . 

61.2 

4.6 

.6 

1.6 

13.5 

13.7 

Mar.  9 . 

59.8 

5.3 

.6 

1.5 

14.0 

14.5 

Mar.  9-10 . 

65.6 

5.7 

.7 

1.4 

13.4 

13.4 

Mar.  10 . 

1 

66.4 

5.7 

.9 

1.5 

13.1 

13.5 

1  The  urine  collected  for  steer  C  during  this  period  was  all  that  could  be  caught.  It  is  esti¬ 
mated  to  be  about  one-third  of  the  total  urination. 


118 


METABOLISM  OF  THE  FASTING  STEER 


Table  30. — Partition  of  nitrogen  excreted  in  urines  of  fasting  steers — Continued 


Proportion  of  total  nitrogen  in — 

Date  and  steer 

Urea 

Am¬ 

monia 

Amino 

acids 

Hip- 

puric 

acid 

Pre¬ 

formed 

creati¬ 

nine 

Total 

creati¬ 

nine 

Steer  D — Cont.  1924. 

p.  ct. 

p.  ct. 

p.  ct. 

p.  ct. 

p.  ct. 

p.  ct. 

Mar.  10-11 . 

74.4 

4.2 

0.6 

1.5 

13.4 

13.6 

Mar.  11 . 

71.2 

6.1 

1.3 

.  .  .  . 

13.1 

12.7 

Mar.  11-12 . 

71.5 

5.0 

.8 

1.5 

15.9 

15.4 

Mar.  12 . 

62.8 

7.5 

.8 

2.1 

15.5 

16.2 

Mar.  12-13 . 

53.9 

5.2 

.8 

2.8 

17.3 

18.4 

Mar.  13 . 

50.1 

8.0 

1.0 

4.7 

17.6 

18.3 

Mar.  13-14 . 

47.1 

8.9 

1.8 

8.2 

21.1 

22.0 

Mar.  14 . 

34.7 

7.2 

1.4 

9.8 

19.3 

20.5 

Mar.  14-15 . 

38.7 

5.2 

3.2 

15.9 

23.2 

23.9 

Steer  E: 

Feb.  11-12 . 

18.2 

38.1 

15.0 

5.6 

4.2 

8.0 

Feb.  12 . 

16.3 

6.1 

6.2 

11.9 

Feb.  12 . 

15.6 

22.7 

6.2 

13.8 

9.2 

13.5 

Feb.  12-13 . 

28.2 

16.2 

7.9 

15.2 

11.8 

15.5 

Feb.  13-14 . 

53.3 

7.6 

3.8 

7.1 

11.3 

13.5 

Feb.  14 . 

66.0 

7.2 

1.4 

4.4 

9.3 

13.8 

Feb.  14 . 

68.1 

6.3 

1.4 

3.7 

8.6 

14.5 

Feb.  14-15 . 

62.1 

3.2 

.7 

3.0 

11.3 

18.3 

Feb.  15 . 

61.1 

3.9 

.7 

.... 

9.6 

15.1 

Feb.  15 . 

60.5 

5.2 

.9 

.... 

9.6 

15.1 

Feb.  15-16 . 

62.9 

8.5 

1.4 

.... 

7.3 

13.2 

Feb.  16 . 

.... 

.... 

1.0 

1.8 

6.4 

12.6 

Feb.  16 . 

.... 

2.6 

.9 

6.7 

13.0 

Feb.  16-17 . 

50.4 

10.9 

1.0 

1.9 

7.6 

13.2 

Feb.  17 . 

53.9 

12.9 

1.7 

1.8 

8.1 

13.4 

Feb.  17 . 

50.0 

7.6 

.8 

.... 

11.9 

18.0 

Feb.  17-18 . 

1  54.8 

117.0 

16.3 

14.5 

1 8.4 

*13. 6 

Feb.  18-19 . 

21.6 

16.9 

8.0 

17.1 

9.2 

12.1 

Feb.  19 . 

25.7 

8.1 

9.3 

18.0 

12.7 

16.6 

Feb.  19-20 . 

19.6 

11.2 

8.4 

25.6 

14.9 

16.3 

Feb.  20 . 

11.2 

9.0 

8.1 

23.2 

16.2 

17.8 

Steer  F: 

Feb.  11-12 . 

38.5 

13.9 

15.9 

21.7 

9.7 

12.4 

Feb.  12 . 

39.9 

10.7 

8.1 

.... 

9.5 

12.3 

Feb.  12-13 . 

19.2 

10.6 

6.1 

18.2 

12.2 

15.1 

Feb.  13 . 

2  25.5 

2 11.4 

2  4.8 

.... 

2 14.2 

2 17.6 

Feb.  13 . 

42.8 

12.9 

7.0 

.... 

13.1 

16.2 

Feb.  13 . 

20.2 

3.8 

2.5 

.... 

18.2 

20.8 

Feb.  13-14 . 

62.6 

3.5 

2.6 

5.9 

13.0 

15.4 

Feb.  14 . 

.... 

.... 

.... 

.... 

12.4 

14.9 

Feb.  14-15 . 

57.0 

2.4 

.8 

2.6 

11.2 

17.9 

Feb.  15 . 

36.2 

2.1 

.4 

.... 

9.7 

16.8 

Feb.  15-16 . 

64.9 

3.9 

.8 

1.6 

9.7 

15.4 

Feb.  16 . 

63.4 

4.9 

.4 

.... 

8.7 

13.8 

Feb.  16-17 . 

70.1 

5.2 

.5 

1.3 

10.0 

14.6 

Feb.  17 . 

69.2 

6.4 

.4 

.... 

8.7 

12.5 

Feb.  17-18 . 

71.5 

6.8 

.7 

1.3 

8.7 

12.4 

Feb.  18 . 

28.2 

6.9 

.8 

.... 

10.2 

15.4 

Feb.  18-19 . 

50.3 

6.6 

.9 

3.2 

9.3 

14.7 

Feb.  19-20 . 

52.7 

8.5 

2.1 

10.8 

10.6 

11.7 

Feb.  20 . 

35.8 

8.9 

3.0 

16.1 

11.1 

12.7 

1  This  urine  was  contaminated  by  a  small  amount  of  feces. 

2  This  mine  is  only  a  portion  of  the  mine  for  the  period.  About  300  grams  of  urine  were  lost. 


URINE 


119 


The  younger  animals  in  their  fast  at  the  submaintenance  level  presented 
a  different  picture  in  some  ways.  The  findings  are  essentially  the  same  for 
both  steers.  In  the  first  place,  the  total  amount  of  nitrogen  varies  con¬ 
siderably.  There  is  a  tendency  for  the  urea-nitrogen  to  increase.  There  is 
great  variability  in  the  ammonia-nitrogen,  a  decrease  in  the  amino-acid  and 
hippuric-acid  nitrogen,  and  a  striking  increase  in  the  creatinine,  both  pre¬ 
formed  and  total.  The  considerable  difference  between  the  preformed  and 
total  creatinine  indicates  that  these  animals  excreted  creatine.  When  feed 
is  given  after  the  fast,  there  is  a  great  fall  in  the  total  nitrogen  per  hour,  a 
decrease  in  the  urea-nitrogen  and  the  ammonia-nitrogen,  an  increase  in  the 
amino-acid  and  hippuric-acid  nitrogen,  essential  constancy  in  the  preformed 
creatinine,  and  a  great  decrease  in  the  total  creatinine,  particularly  after 
the  first  period  of  refeeding. 

Since  the  total  nitrogen  excretion  changed  during  fasting,  a  more  careful 
interpretation  of  these  changes  in  the  nitrogenous  ingredients  can  be  secured 
only  by  a  study  of  the  proportion  of  nitrogen  excreted  in  the  various  forms 
and  the  changes  in  these  proportions  as  time  goes  on.  The  data  for  this 
study  are  shown  in  Table  30. 

Urea  and  ammonia-nitrogen — From  an  examination  of  the  distribution  of 
the  nitrogen  it  is  seen  that  during  fasting  the  urea-nitrogen  becomes  a  greater 
proportion  of  the  total  urinary  nitrogen  than  it  is  during  feeding,  and  that 
with  the  resumption  of  food  the  urea  becomes  a  smaller  proportion  of  the 
total  nitrogen  eliminated.  Unfortunately,  the  only  experiments  in  which 
the  urea-nitrogen  was  determined  by  itself  are  in  the  fasts  with  the  four 
animals  in  1924,  at  the  submaintenance  level.  In  the  November  fasts  in 
1923  the  proportion  of  total  nitrogen  in  the  combined  urea  and  ammonia- 
nitrogen  remains  essentially  constant  as  the  fast  progresses.  In  the  1924 
fasts,  on  the  contrary,  the  nitrogen  from  urea  rises  rapidly  from  26  per 
cent  on  March  3  with  steer  C  to  70  per  cent  or  over  at  the  end  of  the  fast. 
Low  proportions  are  noted  in  the  fasts  with  the  other  animals  likewise,  from 
as  low  as  33  per  cent  with  steer  D  to  15  per  cent  with  steer  E  and  19  per  cent 
with  steer  F.  In  the  case  of  all  four  animals  the  percentage  of  urea-nitrogen 
rises  as  the  fast  progresses,  approaching  finally  a  proportion  that  is  com¬ 
monly  found  with  humans  or  carnivorous  animals  subsisting  upon  a  nitro¬ 
gen-free  diet.  The  subsequent  taking  of  food  in  these  experiments  has  a 
most  profound  effect  upon  this  proportion  in  that  after  the  first  two  days 
the  percentage  of  urea-nitrogen  tends  to  be  low,  corresponding  to  the  initial 
values.  The  ammonia-nitrogen  was  likewise  determined  in  the  four  experi¬ 
ments  at  the  submaintenance  level.  The  values  during  the  fasts  are  low  in 
general,  and  suggest  that  there  was  no  particular  call  for  extra  ammonia  to 
neutralize  any  acid  formation.  For  the  most  part  the  figures  are  regular  in 
all  four  fasts.  It  is  a  noticeable  fact  that  with  all  the  steers  the  taking 
of  food  in  practically  every  case  raises  the  proportion  of  ammonia-nitrogen 
excreted  in  urine.  In  certain  instances,  notably  in  the  experiment  with 
steer  E  prior  to  the  fast  and  even  on  the  first  day  of  the  fast,  the  very  high 
ammonia  values  suggest  the  possibility  that  the  urine  may  have  decomposed. 

Hippuric-acid  nitrogen — In  this  determination  one  obtains  the  amount  of 
benzoic  acid  present,  and  one  must  assume  that  the  nitrogen  was  combined 


120 


METABOLISM  OF  THE  FASTING  STEER 


with  benzoic  acid  to  form  hippuric  acid.  We  have  already  seen  that  there 
is  a  tendency  for  the  amount  of  hippuric-acid  nitrogen  to  decrease  as  the 
fast  goes  on.  This  is  also  shown  by  the  percentage  values,  which  fall 
appreciably.  With  the  resumption  of  feeding  the  values  increase  again. 
The  absolute  values  for  hippuric-acid  nitrogen  excreted  by  all  four  of  these 
animals,  as  shown  in  Table  29,  are  closely  alike  during  the  fasting-periods. 
It  seems  singular  that  animals  with  such  large  differences  in  body-weight 
should  have  such  uniformity  in  this  excretion.  Indeed,  this  finding  suggests 
that  there  is  a  constancy  in  the  hippuric  acid  eliminated,  indicating  that  it 
is  of  endogenous  origin. 

Preformed  creatinine — Folina  attracted  the  attention  of  physiologists  to 
the  significance  of  creatinine  in  protein  metabolism.  The  existence  of 
creatinine  in  the  body  in  the  form  of  creatine  and  creatinine  and  the  fact 
that  creatine  has  been  found  in  the  urines  of  fasting  humans  led  to  our 
determining  both  in  these  samples.  As  has  been  already  pointed  out,  the 
total  amount  of  preformed  creatinine  remains  relatively  constant  with  the 
adult  animals.  This  holds  true  to  a  certain  extent  with  the  total  creatinine 
also,  but  the  younger  animals  show  very  different  reactions  and  indicate  a 
considerable  excretion  of  creatine  as  such.  The  creatinine  elimination  of 
steers  E  and  F  is  smaller  than  that  of  the  larger  steers,  C  and  D.  The  per¬ 
centage  of  the  total  nitrogen  in  the  form  of  preformed  creatinine  was  fairly 
constant  in  the  fast  in  November  1923,  with  a  tendency  to  increase.  On  the 
contrary,  in  the  fasts  at  the  submaintenance  level,  particularly  with  the  two 
older  animals,  there  was  a  distinct  decrease  in  the  percentage  of  nitrogen 
excreted  in  this  form  as  the  fast  progressed. 

Total  creatinine — The  total  creatinine  expresses  the  preformed  creatinine 
plus  any  creatine  which  has  been  converted  by  hydrolysis  into  creatinine. 
In  the  November  fasts  of  1923  there  is  a  distinctly  greater  amount  of  total 
creatinine  than  preformed  creatinine,  showing  excretion  of  creatine  as  such. 
In  the  fasts  of  the  larger  animals  in  1924,  at  the  submaintenance  level,  a 
difference  between  the  preformed  and  the  total  creatinine  is  to  be  found  only 
during  the  first  part  of  the  fast.  With  steers  E  and  F  the  differences  between 
preformed  and  total  creatinine  are  more  marked  than  with  steers  C  and  D 
in  the  fasts  after  submaintenance  feeding.  Indeed,  a  considerable  propor¬ 
tion  of  the  creatinine  is  in  the  form  of  creatine.  The  difference  between  the 
two  creatinines  actually  persists  for  some  little  time,  even  after  food  is 
taken.  It  thus  seems  that  the  smaller  animals  were  much  more  affected  by 
fasting,  as  evidenced  by  the  increasing  elimination  of  creatine,  but  with  the 
larger  animals  the  data  would  suggest  that  during  feeding  there  was  a 
constant  elimination  of  creatine. 

Creatine — From  the  findings  with  steers  C  and  D  in  the  fasts  in  Novem¬ 
ber  1923,  that  is,  after  full  pasturage,  when  a  rather  striking  excretion  of 
creatine  is  shown,  one  could  argue  that  on  feed  there  is  a  regular  excretion 
ol  creatine,  which  disappears  when  the  animal  fasts  at  a  lower  nutritive 
plane.  This  is  contrary  to  the  experience  with  humans,  with  whom  as  the 
fast  progresses  there  is  an  increased  excretion  of  creatine.  The  appearance 
of  creatine  in  the  urine  during  feeding,  particularly  in  the  case  of  the  two 

a  Folin,  Am.  Journ.  Physiol.,  1905,  13,  p.  83. 


URINE 


121 


smaller  steers,  prior  to  the  fast  and  shortly  after  refeeding,  was  again 
rather  unusual.  Dr.  Carpenter  suggests  that  this  may  be  due  not  to  the 
fact  that  creatine  is  a  metabolic  product  but  to  the  fact  that  the  urine 
actually  decomposes  in  the  bladder  of  the  animal  before  it  is  voided.  When 
one  recalls  that  the  urines  of  herbivora  are  highly  alkaline,  it  does  not  seem 
impossible  that  the  retention  of  such  a  fluid  at  body-temperature  might 
result  in  the  change  from  creatinine  to  creatine.  As  a  matter  of  fact,  one 
of  Carpenter’s  experiments  has  shown  that  when  creatinine  was  added  to 
one  of  these  urines  it  disappeared  quickly.  After  the  urine  is  voided,  there¬ 
fore,  it  is  practically  impossible  to  keep  the  creatinine  for  any  considerable 
length  of  time.  This  suggestion  is  of  interest  and  of  importance  because  it 
points  to  the  possibility  of  the  composition  of  freshly  voided  urine  being  due 
not  solely  to  the  constituents  secreted  but  to  a  chemical  change  towards  an 
equilibrium  which  takes  place  before  the  urine  is  voided.  Thus,  it  is  more 
than  likely  that  when  one  is  dealing  with  the  composition  of  urine  from 
such  animals,  one  must  consider  that  the  reaction  of  the  urine  before  it  is 
voided  and  the  length  of  time  it  remains  in  the  bladder  will  affect  the  actual 
chemical  nature  of  the  excreted  liquid.  A  striking  point  in  connection  with 
the  creatine  is  that  throughout  the  fasts  with  steers  E  and  F  there  was  a 
continual  excretion,  which  was  contrary  to  the  finding  with  steers  C  and  D. 
One  explanation  may  be  that  the  reserve  stores  of  these  two  animals,  E  and 
F,  were  not  sufficient  to  supply  an  adequate  portion  of  the  energy  due  to 
carbohydrate  and  fat,  so  that  these  two  younger  animals  gradually  had  to 
call  upon  their  store  of  protein  and  this  disintegration  of  tissue  resulted  in 
the  liberation  of  creatine. 


OTHER  URINARY  CONSTITUENTS 

For  a  detailed  discussion  of  the  various  forms  of  sulphur,  phenols,  acid 
bodies,  fixed  bases,  and  organic  acids  reference  must  be  made  to  Dr.  Car¬ 
penter’s  more  complete  treatment  of  these  data.  Extraordinarily  small 
amounts  of  phosphorus  were  found,  so  that  excretion  of  phosphorus  in  the 
urine  can  hardly  be  considered  of  any  significance  in  the  fasting  steer.  The 
phenols,  which  serve  as  indications  of  a  putrefactive  change  along  with  the 
ethereal  sulphates,  decrease  rather  rapidly  as  the  fast  progresses,  although 
it  is  to  be  borne  in  mind  that  there  are  a  number  of  putrefactive  changes  in 
the  intestinal  tract  for  a  considerable  time  after  the  last  feed  has  been  given. 
The  acid  bodies,  acetone  and  diacetic  acid,  and  /?-oxybutyric  acid,  were 
present  under  practically  all  conditions,  but  frequently  only  in  traces.  The 
important  thing  is  that  these  acid  bodies  were  likewise  noted  on  food  days, 
and  hence  the  conclusion  is  reached  that  fasting,  contrary  to  the  conditions 
with  humans,  does  not  alter  the  excretion  of  these  bodies  with  steers. 

TOTAL  NITROGEN  EXCRETION  PER  KILOGRAM  OF  BODY-WEIGHT  PER  24  HOURS 

In  the  consideration  of  these  fasts  thus  far  particular  stress  has  been  laid 
upon  the  influence  of  the  fast  upon  the  nitrogen  excretion  from  hour  to  hour 
as  the  fast  progresses.  These  animals  had  varying  body-weights,  steers  C 
and  D  being  larger  than  the  younger  steers,  E  and  F.  The  nitrogen  excreted 


122 


METABOLISM  OF  THE  FASTING  STEER 


per  kilogram  of  body-weight  is  therefore  of  interest.  With  the  two  large 
animals,  C  and  D,  the  nitrogen-level  is  much  the  same.  In  the  case  of  steer 
C,  for  example,  the  values  vary  from  as  high  as  0.237  to  as  low  as  0.074  gm. 
at  the  end  of  the  tenth  day  in  the  fast  in  January  1922,  and  in  the  April 
fast  of  1922  a  value  as  low  as  0.073  gm.  was  found  on  the  tenth  day.  The 
values  noted  in  the  fasts  at  the  submaintenance  level  are  much  lower  than 
those  in  the  fasts  at  the  maintenance  level.  Indeed,  with  steer  C  a  very  low 
value  of  0.032  gm.  is  noted  in  the  March  fast,  the  highest  value  being  0.067 
gm.  Similarly,  with  steer  D,  very  low  values  are  observed  during  the  March 
fast  following  submaintenance  feeding,  the  lowest  value  being  0.042  gm. 
With  the  younger  animals,  E  and  F,  the  nitrogen  per  kilogram  of  body- 
weight  per  24  hours  during  the  fasting  period  is  perceptibly  high  and  has  a 
distinct  tendency  to  increase  as  the  fast  progresses.  Contrary  to  the  obser¬ 
vations  on  the  larger  steers,  this  suggests  that  the  reserves  in  the  smaller 
animals  were  not  so  great,  and  consequently  the  demand  for  energy  supply 
was  met  by  an  increasing  utilization  of  body  protein.  This  belief  is  con¬ 
firmed  by  the  fact  that  the  taking  of  food  greatly  decreases  the  excretion 
of  nitrogen  per  kilogram  of  body-weight  per  24  hours.  Thus,  in  the  case  of 
steers  C  and  D  there  was  a  slight  decrease  after  the  ingestion  of  food,  and 
with  steers  E  and  F  there  was  a  noticeable  decrease. 

CREATININE  COEFFICIENT 

The  relationship  between  the  total  amount  of  preformed  creatinine  and 
the  body-weight  of  the  animal  has  attained  considerable  importance,  that 
is,  the  actual  number  of  milligrams  of  preformed  creatinine  per  kilogram  of 
body-weight  per  24  hours.  This  relationship  has  been  computed  for  the 
four  fasts  in  1924  at  the  submaintenance  level,  and  has  been  found  to  remain 
relatively  constant  throughout  the  fast.  In  the  case  of  steer  C,  27.2  mg.  of 
preformed  creatinine  were  excreted  per  kilogram  of  body-weight  per  24  hours 
on  the  day  before  the  fast,  March  2-3.  On  the  first  day  of  the  fast  this 
ratio  fell  to  21  mg.  and  was  relatively  constant  throughout  the  fast.  Dur¬ 
ing  the  two  days  following  the  fast  there  was  likewise  no  appreciable 
alteration.  Indeed,  with  both  animals  the  creatinine  coefficient  was  reason¬ 
ably  constant  when  computed  on  the  basis  either  of  preformed  creatinine  or 
total  creatinine.  With  the  younger  steers,  E  and  F,  however,  although  the 
preformed  creatinine  per  kilogram  of  body-weight  remains  essentially  con¬ 
stant,  the  coefficient  for  the  total  creatinine  becomes  appreciably  higher  as 
creatine  is  excreted.  The  two  younger  animals  agree  between  themselves, 
but  show  distinctly  higher  coefficients  than  do  the  two  adult  animals. 

THE  NITROGEN  ECONOMY  OF  STEERS 

Unfortunately,  the  method  for  determining  hippuric  acid  is  really  a 
method  for  determining  benzoic  acid.  Consequently,  we  do  not  know 
whether  there  may  not  have  been  a  hydrolysis  of  the  hippuric  acid  in  the 
bladder,  so  that  free  amino-acid  was  formed  and  subsequently  determined 
in  the  amino-acid  determination.  If  this  amino-acid  was  not  free,  but  was 
combined  with  the  benzoic  acid,  then  besides  free  amino-acid  considerable 
amounts  of  nitrogen  were  eliminated  in  the  form  of  combined  amino-acid 
with  the  benzoic  acid.  Because  of  the  low  digestibility  of  many  of  the  feed- 


URINE 


123 


stuffs,  particularly  the  roughage  and  grasses  used  by  herbivora,  and  because 
of  the  relatively  large  amounts  of  nitrogen  liberated  in  the  form  of  amino- 
acid,  whether  free  or  combined  with  benzoic  acid,  the  efficiency  of  the 
utilization  of  nitrogen  by  the  steer  is  extremely  low.  Consequently,  as  a 
source  of  obtaining  protein  economically  from  the  nitrogen  cycle,  these 
animals  are  seemingly  very  inefficient.  When  the  formation  of  protein  or 
the  addition  of  muscle,  or  protein  storage,  is  the  main  object  of  feeding,  it 
seems  from  the  results  of  these  urine  analyses  that  it  is  of  the  highest 
importance  to  know  what  proportion  of  the  nitrogen  escaped  into  the  urine 
in  a  form  which  was  not  available  for  metabolic  processes,  namely,  in  the 
amino-acid  form  and  as  hippuric  or  benzoic  acid  combined  with  amino-acid. 
It  therefore  should  be  important  to  determine  which  type  of  ration  results 
in  the  more  economical  use  of  the  protein  ingested,  a  ration  composed  only 
of  roughages,  such  as  hays  and  grasses,  or  a  ration  composed  of  a  roughage 
combined  with  a  grain  or  meal  mixture. 

Studies  are  needed  in  which  the  hippuric  acid  as  such  is  determined,  as 
well  as  the  benzoic  acid,  in  order  to  determine  whether  it  is  eliminated  in 
the  combined  or  free  form,  together  with  the  determination  of  amino-acid  as 
such  by  the  regular  amino-acid  method.  These  animals  were  on  an 
extremely  low  nitrogen-level.  Possibly  with  a  higher  nitrogen-level  a  larger 
proportion  of  nitrogen  might  be  eliminated  as  urea  and  relatively  less  as 
amino-acid  and  hippuric  acid.  It  can  be  seen  from  the  course  of  the  per¬ 
centage  distribution,  however,  that  as  the  animal  tends  to  live  more  and 
more  on  its  own  body-substance,  the  composition  of  the  urine  and  the  dis¬ 
tribution  of  the  urinary  nitrogen  become  more  like  that  in  the  human  being. 
It  would  seem  that  the  nearer  the  ruminant  was  to  its  natural  condition  of 
food  intake,  proportionately  greater  was  the  loss  in  nitrogen  in  forms  which 
had  not  undergone  metabolic  changes  or  had  not  become  an  integral  part 
of  the  body. 

GENERAL  CONCLUSIONS  WITH  REGARD  TO  THE  COMPOSITION  OF  STEER’S  URINE  DURING  FASTING 

Prior  to  fasting,  herbivorous  animals  are  subsisting  upon  a  ration  strik¬ 
ingly  different  from  the  body  substances.  During  fasting  the  large  ballast 
in  the  alimentary  tract  supplies  certain  materials  for  some  time,  but  as  the 
ballast  becomes  exhausted,  the  animal  gradually  begins  to  subsist  solely 
upon  its  own  tissue  deposits  and  hence,  in  a  certain  sense,  becomes  a  carniv¬ 
orous  animal.  During  the  considerable  period  of  time,  possibly  7  days,  when 
the  ballast  is  passing  through  the  alimentary  tract,  the  animal  is  gradually 
changing  from  a  condition  in  which  it  existed  entirely  on  vegetable  food  to 
one  of  fasting,  i.  e.,  subsisting  solely  on  its  own  body-tissue.  At  the  begin¬ 
ning  the  urine  is  alkaline.  Gradually,  however,  its  high  alkalinity  disap¬ 
pears,  and  in  general  after  4  or  5  days  the  urine  reacts  acid  to  litmus  paper. 
During  this  period  the  most  marked  change  in  the  character  of  the  urine  is 
in  the  distribution  of  the  nitrogen.  At  first,  owing  to  the  preponderance  of 
food  residue  in  the  intestines,  the  materials  in  the  urine  are  derived  in  part 
directly  from  the  food.  With  ruminants  one  of  the  most  characteristic  of 
these  materials  is  hippuric  acid,  but  as  the  effect  of  the  previous  food  disap¬ 
pears,  the  hippuric  acid  greatly  diminishes.  On  the  contrary,  urea,  which 
is  found  in  the  urine  of  humans  and  carnivora  in  a  much  higher  percentage, 


124 


METABOLISM  OF  THE  FASTING  STEER 


is  very  low  in  steer’s  urine  when  he  subsists  on  food,  and  one  of  the  first 
striking  changes  in  steer’s  urine  during  fasting  is  a  reversal  of  the  propor¬ 
tions  between  these  two  constituents,  that  is,  a  lowering  of  the  nitrogen  due 
to  hippuric  acid  and  a  gradual  increase  in  the  nitrogen  due  to  urea.  In  the 
fasts  at  the  submaintenance  level  the  percentage  values  for  urea  finally 
approach  those  found  for  the  urines  of  man.  These  figures,  together  with 
the  estimate  of  a  comparable  nitrogen  figure  per  24  hours  for  man,  indicate 
that  the  animals  were  on  a  very  low  nitrogen  plane,  due  to  the  submain¬ 
tenance  feeding.  A  further  indication  of  the  low  nitrogen-level  is  suggested 
by  the  relatively  high  percentage  of  nitrogen  due  to  creatinine.  The  quan¬ 
titative  elimination  of  preformed  creatinine,  as  Folin  has  shown,0  is  inde¬ 
pendent  of  the  nitrogen-level;  therefore,  the  lower  the  nitrogen-level  the 
higher  is  the  percentage  of  preformed  creatinine  nitrogen.  Thus,  in  the  fasts 
of  steers  C  and  D  after  pasture  in  November  1923,  the  preformed  creatinine 
nitrogen  was  from  5  to  9  per  cent  of  the  total  nitrogen  excretion.  In  the 
March  fasts  at  the  submaintenance  level  it  was  from  12  to  27  per  cent,  but 
the  amounts  per  hour  were  nearly  the  same  in  these  two  fasts  with  each 
steer.  Likewise  the  amino-acid  was  relatively  high  at  the  start,  and  then 
fell  to  a  low  figure. 

Another  feature  of  the  urines  of  these  herbivora  during  fasting  is  the  very 
low  ammonia- content.  Man  develops  acidosis  during  fasting,  but  herbivora 
do  not,  for  they  excrete  extraordinarily  small  amounts  of  acetone  bodies  and 
/?-oxybutyric  acid.  Even  the  younger  animals,  E  and  F,  show  a  similar 
resistance  to  the  effect  of  fasting,  so  far  as  the  development  of  acidosis  and 
ketonuria  is  concerned.  The  respiratory  quotients  of  these  animals,  as  will 
be  seen  later  (see  pp.  157  to  161),  approached  the  quotient  indicating  a  com¬ 
bustion  of  pure  fat,  hence  seemingly  an  ideal  condition  for  the  development 
of  ketonuria.  Obviously,  it  is  not  a  universal  biological  phenomenon  that 
ketone  bodies  are  developed  when  the  proportion  of  carbohydrate  to  fat  is 
low.  This  has  great  significance  in  the  study  of  the  keto  and  anti-ketogenic 
ratio,  such  as  is  being  applied  clinically  with  man.  Dr.  Carpenter  suggests 
that  it  may  be  questioned  whether  the  cause  of  and  development  of  ketosis 
on  the  part  of  man  is  due  to  the  low  proportion  of  carbohydrate  or  is  due  to 
the  character  of  the  material  which  is  drawn  upon  when  the  carbohydrate 
in  the  diet  is  diminished.  It  is  difficult  to  understand  why  man  should  differ 
in  this  respect  from  other  animals,  which  in  their  metabolism  show  other 
characteristics  which  are  similar  to  those  noted  with  man.  The  problem 
really  demands  attention  from  a  standpoint  other  than  that  of  the  pure 
relationship  of  carbohydrate  to  fat. 

In  comparing  these  experiments  on  steers  with  those  on  obese  humans  it 
seems  that  the  ability  to  use  fat  and  not  develop  acidosis  is  present  when 
there  is  a  low  nitrogen  excretion.  This  is  in  full  conformity  with  Petren’s 
experience  with  diabetics  on  diets  high  in  fat  and  low  in  protein.* 6  The 
question  arises  as  to  whether  the  utilization  of  fat,  in  protein  and  carbo¬ 
hydrate  withdrawal,  is  not  actually  favored  by  a  low  nitrogen-level. 

The  proportion  of  total  nitrogen  excreted  as  creatinine  may  be  used  as  an 
indication  of  the  nitrogen-level,  that  is,  the  lower  the  proportion  of  nitrogen 

“  Folia,  Am.  Journ.  Physiol.,  1905,  13,  p.  84. 

6  Petr6n,  Proc.  XI  Internat.  Physiol.  Congress.  1923;  ibid.,  Diabetes-Studier,  Copenhagen, 
1923. 


UEINE 


125 


Table  31. — Total  nitrogen  loss  during  fasts  of  5  to  14  days1 


Date 

Steer  C 

Steer  D 

Nitrogen 

in 

urine 

Nitrogen 

in 

feces 

Total 

nitrogen 

loss 

Nitrogen 

in 

urine 

Nitrogen 

in 

feces 

Total 

nitrogen 

loss 

1921 

gm. 

gm. 

gm. 

gm. 

gm. 

gm. 

Nov. 

26  to  Dec.  6 . 

(59.4) 

(57.5) 

Dec. 

6-  7 . 

64.7 

(62.6) 

127.3 

49.3 

(71.8) 

121.1 

Dec. 

7-8 . 

60.0 

(26.3) 

86.3 

50.7 

(18.2) 

68.9 

Dec. 

8-9 . 

81.5 

(21.2) 

102.7 

48.3 

(7.3) 

55.6 

Dec. 

9-10 . 

42.3 

(6.0) 

48.3 

61.2 

(14.8) 

76.0 

Dec. 

10-11 . 

50.8 

(6.4) 

57.2 

*32.7 

(6.0) 

38.7 

Dec. 

11-12 . 

55.5 

(5.8) 

61.3 

53.1 

(8.8) 

61.9 

Dec. 

12-13 . 

42.7 

(4.6) 

.  47.3 

50.7 

(6.9) 

57.6 

Total . 

397.5 

(132.9) 

530.3 

346.0 

(133.8) 

479.8 

1922 

Dec. 

22  to  Jan.  4 . 

(95.5) 

(101.5) 

Jan. 

4-5 . 

123.0 

65.1 

188.1 

122.0 

61.0 

183.0 

Jan. 

5-6 . 

118.0 

26.2 

144.2 

89.9 

28.4 

118.3 

Jan. 

6-7 . 

89.8 

14.5 

104.3 

85.4 

11.1 

96.5 

Jan. 

7-8 . 

44.2 

6.6 

50.8 

66.8 

8.4 

75.2 

Jan. 

8-9 . 

66.9 

8.1 

75.0 

57.0 

7.4 

64.4 

Jan. 

9-10 . 

62.3 

6.2 

68.5 

49.9 

5.2 

55.1 

Jan. 

10-11 . 

37.1 

6.5 

43.6 

55.7 

6.9 

62.6 

Jan. 

11-12 . 

43.6 

3.5 

47.1 

37.8 

4.9 

42.7 

Jan. 

12-13 . 

30.4 

2.9 

33.3 

32.2 

4.0 

36.2 

Jan. 

13-14 . 

44.7 

3.1 

47.8 

35.6 

3.0 

38.6 

Total . 

660.0 

142.7 

802.7 

632.3 

140.3 

772.6 

Mar. 

31  to  Apr.  17 . 

(72.3) 

(76.7) 

Apr. 

17-18 . 

78.2 

60.7 

138.9 

91.1 

63.6 

154.7 

Apr. 

18-19 . 

75.2 

23.8 

99.0 

88.9 

22.4 

111.3 

Apr. 

19-20 . 

67.8 

16.0 

83.8 

78.7 

16.4 

95.1 

Apr. 

20-21 . 

78.6 

12.3 

90.9 

71.1 

12.7 

83.8 

Apr. 

21-22 . 

57.9 

8.2 

66.1 

62.3 

4.8 

67.1 

Apr. 

22-23 . 

63.9 

8.3 

72.2 

56.5 

9.3 

65.8 

Apr. 

23-24 . 

42.9 

5.3 

48.2 

38.9 

6.1 

45.0 

Apr. 

24-25 . 

48.8 

8.1 

56.9 

44.0 

5.1 

49.1 

Apr. 

25-26 . 

52.3 

3.7 

56.0 

38.3 

4.6 

42.9 

Apr. 

26-27 . 

34.3 

2.6 

36.9 

45.1 

3.9 

49.0 

Apr. 

27-28 . 

51.9 

7.1 

59.0 

35.0 

4.3 

39.3 

Apr. 

28-29 . 

36.3 

4.0 

40.3 

37.3 

3.7 

41.0 

Apr. 

29-30 . 

39.7 

3.9 

43.6 

35.8 

3.0 

38.8 

Apr. 

30-May  1 . 

47.2 

3.5 

50.7 

33.9 

2.2 

36.1 

Total . . . 

775.0 

167.5 

942.5 

756.9 

162.1 

919.0 

May 

9  to  June  1 . 

(80.0) 

(82.7) 

June 

1-2 . 

100.0 

68.6 

168.6 

93.8 

61.7 

155.5 

June 

2-3 . 

103.0 

32.9 

135.9 

96.2 

27.5 

123.7 

June 

3-  4 . 

80.5 

19.0 

99.5 

88.1 

20.8 

108.9 

June 

4-  5 . 

62.0 

7.2 

69.2 

66.1 

7.1 

73.2 

June 

5-6 . 

60.8 

9.3 

70.1 

62.9 

10.2 

73.1 

Total . 

406.3 

137.0 

543.3 

407.1 

127.3 

534.4 

1  Values  in  parentheses  are  based  upon  analyses  of  composite  samples;  all  others  are  based 
upon  daily  samples. 

1  Some  urine  lost;  amount  not  known. 


126 


METABOLISM  OF  THE  FASTING  STEER 


Table  31. — Total  nitrogen  loss  during  fasts  of  5  to  14  days 1 — Continued 


Date 

Steer  C 

Steer  D 

Nitrogen 

in 

urine 

Nitrogen 

in 

feces 

Total 

nitrogen 

loss 

Nitrogen 

in 

urine 

Nitrogen 

in 

feces 

Total 

nitrogen 

loss 

1922 

gm. 

gm. 

gm. 

gm. 

gm. 

gm. 

Nov.  6-  7 . 

2  99.0 

47.2 

146.2 

99.4 

47.0 

146.4 

Nov.  7-8 . 

100.6 

27.9 

128.5 

91.6 

23.1 

114.7 

Nov.  8-  9 . 

59.4 

15.6 

75.0 

93.3 

21.6 

114.9 

Nov.  9—10 . 

94.5 

13.6 

108.1 

80.0 

6.5 

86.5 

Nov.  10-11 . 

80.0 

7.7 

87.7 

86.0 

14.3 

100.3 

Nov.  11-12 . 

49.3 

6.4 

55.7 

71.3 

4.7 

76.0 

Nov.  12-13 . 

73.4 

6.1 

79.5 

*47.8 

14.3 

62.1 

Nov.  13—14 . 

66.5 

11.2 

77.7 

54.5 

1.6 

56.1 

Nov.  14—15 . 

72  0 

7  1 

79  1 

Total . 

694.7 

142.8 

837.5 

623.9 

133.1 

757.0 

1923 

Nov.  5-  6 . 

87.0 

(63.4) 

150.4 

81.0 

(63.2) 

144.2 

Nov.  6—  7 . 

95  4 

(38  3) 

133  7 

91  7 

(28  6) 

120  3 

Nov.  7-  8 . 

78.1 

(18.4) 

96.5 

80.5 

(13.9) 

94.4 

Nov.  8-  9 . 

63.6 

(11.3) 

74.9 

73.3 

(15.7) 

89.0 

Total . 

324.1 

(131.4) 

455.5 

326.5 

(121.4) 

447.9 

1924 

Mar.  3- 4  4 . 

15.6 

20.3 

35.9 

18.8 

*  (19.7) 

38.5 

.  Mar.  4—  5 . 

1 

f  31.2 

8  (16.5) 

47.7 

Mar.  5-  6 . 

i6 102.9 

*34.0 

8 136.9 

j  34.1 

14.4 

48.5 

Mar.  6—  7 . 

j 

[  35.8 

5.5 

41.3 

Mar.  7—  8 . 

40.2 

6.5 

46.7 

51.2 

7  (8 . 9 ) 

60.1 

Mar.  8-  9 . 

37.3 

1.1 

38.4 

42.5 

7  (3 . 5 ) 

46.0 

Mar.  9-10 . 

40.4 

4.8 

45.2 

45.4 

4.9 

50.3 

Mar.  10-11 . 

38.7 

3.9 

42.6 

37.1 

6.0 

43.1 

Mar.  11-12 . 

39.0 

2.3 

41.3 

41.1 

3.6 

44.7 

Mar.  12—13 . 

29.7 

8  0  0 

29.7 

Total . 

343.8 

72.9 

416.7 

337.2 

83.0 

420.2 

1  Values  in  parentheses  are  based  upon  analyses  of  composite  samples;  all  others  are  based 
upon  daily  samples. 

s  Some  urine  lost;  amount  not  known. 

3  About  200  gm.  urine  lost. 

4  Mar.  3-4  represents  a  17-hour  period  from  2;p.  m.,  Mar.  3,  to  7  a.  m.,  Mar.  4;  all  other  days 
in  this  fast  begin  and  end  at  7  a.  m. 

1  Based  on  composite  sample  for  Mar.  3  to  5. 

*  Data  for  Mar.  4  to  7  combined,  because  analyses  of  urine  and  feces  were  not  made  in  exact 
24-hour  periods  during  this  time. 

7  Based  on  a  composite  sample  for  Mar.  7  to  9. 

8  There  were  no  defecations  between  7  a.  m.,  Mar.  12,  and  7  a.  m.,  Mar.  13,  but  0.62  kg. 
feces  were  passed  between  7h  10m  and  10h  25m  a.  m.,  Mar.  13,  before  the  steer  was  fed ;  nitrogen 
content  2.38  gm. 

as  creatinine  the  higher  is  the  nitrogen-level.  Steers  E  and  F  were  on  an 
appreciably  higher  plane  in  this  regard  than  were  steers  C  and  D.  On  the 
other  hand,  the  creatinine  coefficient  may  be  taken  as  an  indication  of  the 
reserve  material,  that  is,  as  an  indication  of  whether  the  animal  is  fat  or 
lean,  because  the  fatter  the  animal  the  lower  will  be  this  coefficient. 
Although  it  is  in  the  realm  of  speculation,  one  may  surmise  that  the  appear¬ 
ance  of  creatine  may  be  taken  as  an  indication  of  the  inability  to  utilize  the 
store  of  fat  on  hand  or  the  lack  of  fat  of  an  adequate  chemical  composition. 


NITROGEN  LOSS 


127 


NITROGEN  LOSS 

Total  Nitrogen  Excreted  in  Urine  per  Day  and  During  the  Entire 

Fast 

From  the  physiological  standpoint,  the  interest  in  the  chemical  compo¬ 
sition  of  the  urine  at  the  present  day  far  exceeds  that  in  the  urinary  nitrogen 
loss,  which  for  years  served  as  the  only  chemical  index  of  protein  disintegra¬ 
tion.  The  chemistry  of  the  urine,  however,  deals  for  the  most  part  with  the 
nature  of  the  substances  analyzed  and  their  relative  proportions  in  the 
urine,  and  the  total  urinary  nitrogen  still  remains  the  best  index  of  the  total 
protein  disintegration.  Hence  special  consideration  was  given  to  the  total 
nitrogen  excreted  in  the  urine  in  relation  to  the  previous  state  of  nutrition, 
the  length  of  the  fast,  and  the  age  of  the  animal.  The  total  nitrogen  was 
determined  in  the  weights  of  urine  shown  in  Table  27  (p.  100) ,  secured  in 
the  conventional  24-hour  periods.  As  pointed  out  in  the  discussion  of  this 
table,  however,  these  weights  do  not  represent  exactly  the  urine  excreted  for 
24  hours,  but  simply  the  actual  voidings  occurring  between  the  beginning 
of  the  experimental  day  and  approximately  24  hours  from  that  time.  In 
the  discussion  of  the  chemistry  of  the  urine  this  inequality  in  time  is  in  large 
part  compensated  by  referring  all  the  urinary  excretions  to  the  per  hour 
basis,  but  for  the  purpose  of  studying  the  protein  disintegration  it  seems 
best  to  consider  the  total  urinary  nitrogen  excretion  in  24  hours,  notwith¬ 
standing  the  defect  in  the  24-hour  separation  and  collection. 

The  24-hour  amounts  of  nitrogen  excreted  in  the  urine  have  therefore  been 
given  in  Tables  31  and  32  for  each  day  of  the  long  fasts  as  well  as  the 
average  24-hour  values  for  the  preceding  feed-periods.  (See  also  Tables  28, 
and  29,  pp.  108  and  111,  for  details  of  exact  duration  of  the  period  of  collec¬ 
tion.)  The  data  for  the  feeding-periods  are  separated  from  those  for  the 
fasting-periods  by  horizontal  rules. 


Table  32. — Total  nitrogen  losses  of  steers  E  and  F  during  fast  in  February  1924 


Date 

Steer  E 

Steer  F 

Nitrogen 

in 

urine 

Nitrogen 

in 

feces1 

Total 

nitrogen 

loss 

Nitrogen 

in 

urine 

Nitrogen 

in 

feces1 

Total 

nitrogen 

loss 

1924 

gm. 

gm. 

gm. 

gm. 

gm. 

gm. 

Feb.  11-12 . 

19.8 

20.6 

Feb.  12-13 . 

13.8 

(11.4) 

25.2 

2  10.8 

(15.4) 

26.2 

Feb.  13-14 . 

24.6 

(13.1) 

37.7 

20.2 

(8.5) 

28.7 

Feb.  14-15 . 

22.2 

(7.4) 

29.6 

22.2 

(8.9) 

31.1 

Feb.  15-16 . 

36.4 

(3.9) 

40.3 

32.0 

(4.9) 

36.9 

Feb.  16-17 . 

26.6 

(1.6) 

28.2 

35.5 

(2.7) 

38.2 

Feb.  17-18 . 

. 

. 

32.0 

(1.9) 

33.9 

Total . 

123.6 

(37.4) 

161.0 

152.7 

(42.3) 

195.0 

1  Based  on  analysis  of  composite  sample  for  Feb.  12  to  18.  In  the  case  of  steer  E  this  sample 
included  the  feces  passed  on  the  first  day  on  feed  after  the  fast. 

s  About  10  ounces  of  urine  lost  during  the  day.  ■ 


128 


METABOLISM  OF  THE  FASTING  STEER 


Prior  to  the  fasts,  the  average  daily  excretion  of  urinary  nitrogen  by  steers 
C  and  D  in  the  feed  periods  other  than  at  the  submaintenance  level  varied 
from  57.5  to  101.5  gm.  Inasmuch  as  both  animals  received  exactly  the  same 
treatment,  the  variations  are  much  the  same  with  both.  The  lowest  value 
during  the  feed  periods  occurred  prior  to  the  fast  in  December  1921,  and  the 
highest  prior  to  the  fast  in  January  1922.  In  the  pasture  periods  nitrogen 
determinations  were  not  feasible.  On  March  2-3,  at  the  submaintenance 
level  prior  to  the  fast  in  March  1924,  a  low  amount  of  30  gm.  was  observed 
on  the  average  with  each  animal. 

The  total  loss  of  nitrogen  from  the  body  during  a  fast  will  in  all  prob¬ 
ability  be  determined  in  large  measure  by  the  level  of  the  nitrogen  metabo¬ 
lism  at  the  start  of  the  experiment.  In  those  experiments  following  pro¬ 
longed  undemutrition  it  has  been  noted  with  man  that  an  appreciable  part 
of  the  body  nitrogen  may  be  lost  as  a  result  of  undernutrition;  in  other 
words,  there  is  a  continuous  negative  balance.  When  a  fast  is  started  at  a 
low  nitrogen-level,  obviously  the  drafts  due  specifically  to  the  fast  are  less 
than  when  the  fast  is  started  at  a  higher  level.  Emphasis  in  the  following 
discussion  is  therefore  laid  upon  the  fasts  which  followed  maintenance 
feeding. 

On  the  first  day  of  fasting  following  maintenance  feeding  there  was  in  all 
cases  but  one  an  increase  in  the  urinary  nitrogen  of  steers  C  and  D  as  com¬ 
pared  with  the  average  value  before  the  fast.  In  the  fast  in  December  1921, 
steer  D,  however,  actually  excreted  8  gm.  less.  The  increase  was  very  large 
with  steer  C  in  the  January  1922  fast,  amounting  to  nearly  30  grams.  Until 
the  third  day  the  24-hour  nitrogen  excretion  remained  fairly  constant,  but 
usually  decreased  rapidly  after  the  third  day.  In  the  discussion  of  the 
chemistry  of  the  urine  it  was  pointed  out  (see  p.  115)  that  the  minimum 
nitrogen  excretion  of  steers  C  and  D  was  not  far  from  40  grams  per  24  hours. 
This  excretion  corresponds  essentially  to  that  of  man  on  a  nitrogen-free 
diet.  The  constancy  in  the  daily  amounts  in  the  last  part  of  each  fast  is 
striking. 

The  total  amount  of  nitrogen  lost  from  the  body  in  the  urine  during  each 
of  these  different  fasts  is  likewise  recorded  in  Tables  31  and  32.  Naturally 
the  larger  amounts  were  lost  during  the  longer  fasts,  and  it  can  be  seen 
that  the  14-day  fast  made  a  considerable  draft  upon  the  protein  store  of 
steers  C  and  D.  On  the  assumption  that  each  gram  of  urinary  nitrogen  lost 
from  the  body  represents  6.25  gm.  of  dry  protein  (the  conventional  factor), 
the  maximum  draft  upon  dry  protein  was  4.84  kg.  in  the  case  of  steer  C 
and  4.73  kg.  in  the  case  of  steer  D.  In  both  instances,  as  is  to  be  expected, 
this  maximum  draft  occurred  in  the  14-day  fast.  Multiplication  of  the 
amount  of  dry  protein  by  the  factor  commonly  used  for  the  conversion  of 
protein  to  flesh,  i.  e.,  4.0,  shows  that  steer  C  lost  19.4  kg.  of  flesh  and  steer 
D  lost  18.9  kg.  This  method  of  computation  follows  the  older  usage  of 
ascribing  the  entire  urinary  nitrogen  loss  to  muscle-tissue,  and  although  this 
method  is  obviously  incorrect,  it  gives  a  hint  as  to  the  actual  weight  of 
nitrogen  lost  in  the  breakdown  of  protein.  Since  chemical  analyses  of  the 
bodies  of  these  animals  were  not  made,  a  computation  of  the  percentage  loss 
of  total  protein  is  hardly  significant,  owing  to  the  variations  in  the  propor- 


NITROGEN  LOSS 


129 


tion  of  protein  in  the  body  and  particularly  to  the  fact  that  these  animals 
were  subjected  to  numerous  intermittent  fasts  and  were  on  various  feed 
levels.  It  can  be  seen,  however,  that  there  was  a  substantial  draft  upon  the 
body-tissue  during  the  14-day  fast. 

Total  Nitrogen  Loss  During  Fasts  of  5  to  14  Days 

Although  the  nitrogen  in  the  urine  particularly  represents  protein  metabo¬ 
lism  and  the  nitrogen  in  the  feces  supposedly  unabsorbed  nitrogen  of  food, 
we  have  already  seen  (p.  123)  that  in  the  urine  at  least  hippuric-acid  nitro¬ 
gen  and  amino-acid  nitrogen  may  not  represent  protein  disintegration,  but 
simply  a  path  for  the  excretion  of  food  nitrogen,  which  has  actually  not 
been  metabolized.  Similarly,  it  is  not  inconceivable  that  certain  nitrogenous 
products  in  the  feces,  formerly  grouped  under  the  general  head  of  “metabolic 
fecal  nitrogen,”  may  in  the  case  of  humans  represent  actual  metabolic  trans¬ 
formations.  With  these  reservations  it  may  be  maintained  that  the  nitro¬ 
gen  of  urine  represents  the  disintegration  of  protein,  and  the  nitrogen  of 
feces  unabsorbed  feed  nitrogen.  Considering  the  animal  at  the  beginning 
of  the  fast  as  a  unit  consisting  of  its  organized  body-tissue  plus  the  contents 
of  its  intestinal  tract,  one  may  note  the  total  loss  of  nitrogen  from  this  unit 
during  the  period  of  fasting  by  summing  the  nitrogen  lost  in  the  urine  and 
that  lost  in  the  feces,  without  attempting  to  differentiate  between  the 
urinary  and  fecal  nitrogen  on  the  basis  of  metabolized  or  non-metabolized 
nitrogen.  Such  computations  have  likewise  been  recorded  in  Tables  31 
and  32. 

During  the  fasts  in  December  1921,  November  1923,  and  February  1924, 
the  fecal  nitrogen  was  determined  only  for  the  entire  period  of  the  fast  and 
the  amount  of  nitrogen  has  been  apportioned  between  the  different  days 
upon  the  basis  of  the  fresh  weight  of  feces  passed  daily,  on  the  assumption 
that  the  percentage  of  nitrogen  in  each  day’s  feces  was  the  same  throughout 
the  entire  fasting-period.  This  assumption  is  probably  not  justified,  although 
in  lieu  of  daily  nitrogen  determinations  it  may  be  used  here  tentatively. 
The  same  treatment  has  been  given  to  the  data  for  fecal  and  urinary  nitro¬ 
gen  in  the  feed-periods  preceding  the  fasts,  and  to  certain  data  in  the  fasts  in 
March  1924.  The  values  thus  computed  have  been  inclosed  in  parentheses. 
The  nitrogen  loss  due  to  epidermal  tissue  and  hair,  which  is  a  measurable 
amount,  has  not  been  estimated,  although  Armsby  and,  indeed,  before  him 
Grouven,  took  such  loss  into  consideration. 

In  the  fast  in  April  1922,  steers  C  and  D  each  lost  over  900  grams  of 
nitrogen.  As  is  to  be  expected,  the  total  loss  varies  again  with  the  length 
of  the  fast  and  particularly  with  the  character  of  the  ration  prior  to  the 
fast.  Thus,  since  steers  C  and  D  had  undergone  a  loss  of  nitrogen  when 
receiving  submaintenance  rations  prior  to  the  fasts  in  March  1924,  their 
total  daily  loss  of  nitrogen  during  these  fasts  averaged  not  far  from  40 
grams.  Essentially  the  same  loss  was  noted  after  the  eighth  day  of  fasting 
following  maintenance  feeding.  During  the  fasts  of  steers  E  and  F  in 
February  1924,  the  total  loss  of  nitrogen  was  approximately  30  grams  per 
day  with  each  steer,  indicative  not  only  of  similar  body-weights  but  likewise 
of  the  submaintenance  level  of  nutrition. 


130 


METABOLISM  OF  THE  FASTING  STEER 


Our  data  are  wholly  inadequate  for  the  study  of  the  recovery  after  fast¬ 
ing  and  the  rapidity  of  nitrogen  retention,  as  our  main  problem  was  the 
course  of  the  metabolism  during  complete  fasting.  Substantial  losses  of 
nitrogen  are  experienced  by  steers  when  fasting,  even  when  the  normal 
nitrogen  storage  has  been  considerably  depleted  by  the  prolonged  use  of  a 
submaintenance  ration. 

BODY  MEASUREMENTS,  GENERAL  BODY  CONDITIONS,  AND 

PHYSIOLOGICAL  FUNCTIONS 

Body  Measurements 

General  body  measurements  were  taken  before  and  after  the  fasts  of  five 
or  more  days’  duration.  In  addition,  three  different  body  circumferences, 
namely,  around  the  paunch,  the  flank,  and  the  chest,  were  measured  daily 
during  the  entire  experimental  season.  The  measurements  obtained  at  the 
beginning  and  end  of  the  fasts  are  of  special  interest,  as  they  indicate 
whether  any  marked  changes  have  occurred  that  might  possibly  have  a 
significant  correlation  with  loss  of  body-tissue  and  conceivably  also  with 
changes  in  body-surface  area.  As  a  typical  illustration,  the  general  body 
measurements  secured  at  the  beginning  and  end  of  the  14-day  fast  in  April 
1922  are  recorded  in  Table  33.  Since  this  was  the  longest  fast,  these  data 
will  obviously  indicate  the  maximum  variations  noted  in  the  size  of  the 
measurements  due  to  fasting. 

The  only  body  measurements  which  show  a  significantly  large  decrease 
during  fasting  are  the  circumferences  of  the  middle  part  of  the  body,  some¬ 
times  termed  the  “barrel.”  In  the  order  of  magnitude  the  shrinkage  is 
greatest  at  the  paunch,  slightly  less  at  the  flank,  and  materially  less  at  the 
chest.  In  other  words,  the  shrinkage  at  paunch  and  flank  reflects  largely 
the  loss  in  fill,  the  chest  circumference  being  but  slightly  affected  by  this 
loss.  These  measurements  are  therefore  of  value  chiefly  because  they  might 
conceivably  be  used  as  a  crude  basis  for  estimating  the  change  in  surface 
area.  The  body-length  changes  but  little.  Since  it  is  evidently  one  of 
the  dimensions  which  furnish  fairly  distinct  landmarks  for  repeated  meas¬ 
urements,  it  may  prove  a  useful  measurement  in  connection  with  some  of 
the  more  recent  formulas  for  determining  surface  area.  The  other  dimen¬ 
sional  measurements  have  no  particular  value  as  indicators  of  shrinkage 
during  fasts  not  exceeding  14  days  in  length,  because  for  the  most  part  it 
is  difficult  to  obtain  duplicate  readings  successively,  the  error  introduced 
thereby  often  exceeding  the  most  probable  actual  change.  They  are  valua¬ 
ble  only  in  giving  a  general  idea  of  the  size  and  proportions  of  conformation 
of  the  animal. 

Special  emphasis  was  laid  upon  the  measurement  of  the  chest-girth,  for 
it  had  been  noted  in  an  earlier  study  of  undernutrition  in  steers  that  the 
chest-girth  was  influenced  the  least  by  changes  in  fill  and  that  a  change  in 
this  girth  more  truly  represented  an  actual  alteration  in  the  state  of  flesh. 
Hence  changes  in  chest  circumference  are  of  far  more  significance  quanti¬ 
tatively  than  changes  in  body-weight.  Obviously,  in  making  this  measure¬ 
ment,  care  must  be  taken  to  have  the  traction  on  the  measuring  tape  or 
chain  uniform,  and  it  is  preferable  to  have  the  same  observer  make  the 


BODY  MEASUREMENTS  AND  PHYSIOLOGICAL  FUNCTIONS  131 


measurements  from  day  to  day,  to  insure  both  the  uniform  traction  and 
the  exact  location  of  the  tape. 


Table  33. — General  body  measurements  at  the  beginning  and  end  of  the  14-day  fast 


Measurement 

Steer  C 

Steer  D 

Start 

End 

Difference 

Start 

End 

Difference 

Body  circumferences: 

cm . 

cm. 

cm. 

cm. 

cm. 

cm. 

Chest . 

198.0 

193.0 

5.0 

208.5 

200.5 

8.0 

Paunch . 

228.5 

200.5 

28.0 

228.5 

208.5 

20.0 

Flank  (rear) .... 

198.0 

172.0 

26.0 

200.5 

183.0 

17.5 

Chest  width . 

52.5 

47.0 

5.5 

53.0 

50.0 

3.0 

Chest  depth . 

75.0 

72.0 

3.0 

79.0 

79.0 

0.0 

Width  at  hips . 

57.0 

54.5 

2.5 

62.5 

58.0 

4.5 

Body  length1 . 

160.0 

157.5 

2.5 

165.0 

162.5 

2.5 

Fore  leg  length. ..... 

82.0 

77.5 

4.5 

84.5 

83.0 

1.5 

Hind  leg  length . 

96.0 

95.0 

1.0 

99.0 

99.0 

0.0 

1  Measurement  from  second  dorsal  vertebra  to  pin-bone. 

The  measurements  of  the  chest  circumference  secured  during  the  fasting 
experiments  of  5  to  14  days  are  recorded  in  Table  34,  and,  for  purposes  of 
comparison,  the  measurements  secured  on  the  three  food  days  just  prior 
to  the  fasts  are  also  given.  It  can  be  seen  that  the  normal  variation  in 
this  measurement  to  be  expected  from  day  to  day  during  feeding  usually 
is  not  far  from  2  to  3  cm.,  although  before  the  April  fast  of  steer  C  and 
the  December  fast  of  steer  D  a  variation  of  4  cm.  was  noted.  Shortly  after 
the  beginning  of  the  fast  there  is  a  decrease  in  the  chest-girth,  and  this 
decrease  continues  as  the  fast  progresses,  although  it  is  by  no  means 
uniform.  Thus,  in  the  14-day  fast,  the  chest  circumference  of  steer  C 
decreased  from  198  cm.  at  the  start  to  193  cm.  at  the  end,  that  is,  there 
was  a  total  shrinkage  of  5  cm.  Steer  D,  in  the  corresponding  fast,  lost 
9  cm.  On  the  other  hand,  in  the  fast  after  pasture  in  November  1922,  the 
chest  circumference  of  steer  C  decreased  from  211  to  203  cm.,  a  change  of 
8  cm.  With  the  young  animals  which  fasted  not  over  four  to  five  days 
after  submaintenance  feeding,  the  changes  in  chest  circumference  were 
hardly  outside  the  range  of  the  normal  error  of  observation.  Therefore, 
although,  theoretically  at  least,  the  chest  circumference  should  be  a  fairly 
good  index  of  the  state  of  nutrition  and  the  loss  of  flesh,  practically  it 
serves  only  as  a  general  index  and  can  not  be  considered  as  a  quantitative 
index,  even  in  a  fast  of  from  10  to  14  days. 

Each  of  the  entries  in  this  table  represents  the  chest  circumference  at 
the  beginning  of  the  day.  Records  were  also  made  at  the  end  of  the  last 
fasting  day.  These,  with  one  exception,  show  either  no  change  or  a  decrease 
of  only  1  cm.  as  compared  with  the  circumference  at  the  beginning  of  the 
last  day.  At  the  end  of  the  January  fast  of  steer  D  there  was  a  decrease 
of  3  cm.,  from  206  to  203  cm.  Thus  there  was  no  measurable  loss  during 
the  last  day  of  fasting. 

The  experience  in  using  the  chest  circumferences  in  the  earlier  study  of 
undemutrition  in  steers  had  led  to  the  belief  that  this  was  an  important 


Table  34. — Chest  circumferences  prior  to  and  during  fasts  of  5  to  14  days1 


132 


METABOLISM  OF  THE  FASTING  STEER 


1  The  chest  circumferences  of  steers  C  and  D  were  measured  at  2  p.  m.,  those  of  steers  E  and  F  at  7b30m  a.  m.  As  recorded  in  this  table,  they 
represent  measurements  secured  at  the  beginning  of  each  day. 


BODY  MEASUREMENTS  AND  PHYSIOLOGICAL  FUNCTIONS  133 

physical  measurement,  which  would  give  an  index  of  the  state  of  nutrition 
of  the  animals.  It  is  much  to  be  regretted  that  a  good  index  of  the  state 
of  nutrition  comparable  to  the  numerous  indices  of  state  of  nutrition  now 
available  for  humans  is  not  yet  available  for  animals.  The  personal  equa¬ 
tion  of  the  experienced  judge  will  still  have  to  be  allowed  to  enter  into 
every  estimate  made,  until  a  series  of  girths  or  lengths  or  ratios  to  weight 
can  be  agreed  upon  by  the  majority  of  livestock  judges,  which  will  possibly 
put  this  important  estimate  upon  a  mathematical  basis.  Such  experience 
as  is  outlined  in  Table  34,  however,  is  disconcerting,  and  it  is  clear  that 
one  measurement  alone  may  not  be  considered  as  appropriate  for  such  an 
index.  No  attempt  has  been  made  to  combine  this  measurement  with 
lengths  or  with  weights  or  with  any  functions  of  body-weight,  since  the 
quantitative  expression  of  the  state  of  nutrition  of  animals  is  still  unsettled. 

General  Body  Conditions 

During  each  of  the  fasts  a  daily  record  was  kept  of  all  incidents  relating 
to  the  general  appearance  and  behavior  of  the  fasting  animal,  and  particular 
note  was  made  of  such  reactions  as  could  not  be  measured  or  expressed  in 
terms  of  concrete  data.  These  observations  are  summarized  under  two 
heads,  the  effect  of  fasting  on  general  behavior  and  the  effect  of  fasting 
on  physical  appearance. 

General  Behavior  of  Fasting  Steers 

With  humans,  particularly  in  the  lay  mind,  the  idea  of  fasting  is  always 
inseparably  interwoven  with  food  shortage  under  enforced  conditions,  and 
it  therefore  implies  hardships  and  suffering.  In  animals  the  actual  sensa¬ 
tions,  if  any,  resulting  from  lack  of  food  are  not  obscured  by  the  capacity 
to  reason,  and  their  general  behavior  is  therefore  more  truly  an  expression 
of  the  physical  sense  of  uneasiness  resulting  from  lack  of  food.  In  a  study 
of  steers  during  prolonged  undernutrition0  it  was  found  that  when  the 
ration  was  reduced  from  a  maintenance  ration  to  one  about  half  sufficient 
for  maintenance,  the  steers  showed  some  nervous  irritation  for  a  few  days, 
after  which  those  on  submaintenance  showed  no  more  eagerness  for  food 
than  did  the  steers  which  were  still  on  full  rations.  The  general  deduction 
is  that  the  so-called  “hunger  feeling”  is  merely  the  temporary  sensation 
caused  by  the  physical  contraction  of  the  alimentary  tract  to  meet  the 
requirements  of  a  diminished  bulk,  but  in  no  sense  represents  distress  due 
to  a  lack  of  nourishment  to  the  tissues. 

Disposition  and  behavior — During  the  fasting  experiments  there  was 
always  some  protest  from  the  animals  when  the  first  feed  was  withheld. 
This  was  made  manifest  by  a  continuation  of  the  usual  signs  which  cattle 
exhibit  at  feeding-time.  In  other  words,  they  were  apprehensive  and 
uneasy  for  several  hours  beyond  the  time  when  feed  would  normally  have 
been  given,  at  times  lowing  and  showing  general  nervous  irritation  at  being 
thus  apparently  neglected.  As  a  rule,  they  behaved  very  quietly  by  the 
second  day,  showing  no  particular  sign  of  uneasiness,  irritation,  or  craving 
for  food  except  after  drinking,  when  at  times  they  repeated  their  exertions 


•Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  176, 


134 


METABOLISM  OF  THE  FASTING  STEER 


up  to  the  fifth  or  sixth  day,  although  less  and  less  persistently  than  on  the 
first  day.  Their  placid  and  indifferent  attitude  after  the  first  day  of  fasting 
was,  in  fact,  a  surprise.  On  the  whole,  these  fasting  steers  seemed  to  adjust 
themselves  temperamentally  to  an  entire  lack  of  food  even  more  readily 
than  was  the  case  with  steers  which  were  fed  only  half  a  maintenance 
ration.  Previous  to  the  beginning  of  the  14-day  fast,  when  steers  C  and  D 
were  on  a  ration  containing  9  kg.  of  hay  and  3  kg.  of  meal  (equal  parts 
by  weight  of  com  meal,  linseed  meal,  and  bran),  they  were  very  restless 
and  acted  anxious  for  food  at  meal  time.  On  the  afternoon  of  the  first 
day,  when  their  first  meal  was  withheld,  they  exhibited  this  symptom  to 
a  marked  extent.  On  the  second  day,  although  they  still  showed  a  tendency 
to  nervousness  from  lack  of  food,  they  were  somewhat  more  quiet  and 
seemed  to  spend  less  time  standing  than  when  on  feed.  By  the  end  of  the 
second  day  they  were  very  quiet  and  inactive  and  remained  so  during  the 
rest  of  the  fast,  showing  no  particular  irritation  or  craving  for  food. 

Vigor — Loss  in  vigor  due  to  prolonged  undernutrition  or  to  malnutrition 
in  livestock  is  usually  accompanied  by  a  dull,  listless  expression.  Bright¬ 
ness  of  eye  and  of  general  expression,  on  the  other  hand,  is  ordinarily 
considered  a  characteristic  mark  of  vigor  and  particularly  of  good  health. 
If  these  commonly  accepted  expressions  have  any  basis  of  fact,  then  a 
dull,  listless  expression  may  be  considered  as  a  danger  signal,  suggesting 
that  health  is  being  impaired  or  undermined.  In  no  case  of  fasting  did 
any  of  these  steers  show  any  signs  of  a  lack  of  vigor,  judged  on  this  basis. 
At  the  end  of  the  10-day  fast  in  January  1922,  steers  C  and  D  were  appar¬ 
ently  as  vigorous  as  on  the  third  day,  and  even  at  the  end  of  the  14-day 
fast  they  were  still  as  active  and  alert  as  ever,  when  taken  outdoors  to  be 
photographed.  Both  animals  stood  up  for  much  shorter  intervals  as  the 
fasts  progressed,  but  they  seemed  to  rise  with  apparent  ease,  showing  no 
particular  weakness  in  this  respect,  even  at  the  end  of  the  14-day  fast. 
During  this  fast  they  did,  however,  relax  more  on  going  down,  performing 
the  last  part  of  the  operation  with  more  or  less  of  a  drop,  due  no  doubt 
in  part  to  the  fact  that  they  had  been  confined  in  stalls  for  about  5  months 
and  were  somewhat  stiff  from  lack  of  exercise.  In  general,  they  both 
appeared  as  strong  and  vigorous,  even  on  the  last  day  of  the  14-day  fast, 
as  in  the  early  stages  of  fasting,  their  eyes  being  bright,  indicating  that 
health  or  vigor  had  been  in  no  wise  impaired. 

Muscular  activity — The  close  correlation  between  muscular  activity  and 
metabolism,  observed  so  frequently  with  humans  and  likewise  pointed  out 
with  animals,  made  direct  comparative  records  of  muscular  activity  an 
essential  part  of  our  technique.  With  stall-fed  steers,  practically  the  only 
pronounced  activity  is  that  of  getting  up  and  lying  down.  These  changes 
of  position  were  indicated  in  the  laboratory  room  by  means  of  a  small 
weight  attached  to  one  end  of  a  cord  running  over  pulleys,  the  other  end 
being  attached  to  the  urine  harness,  so  that,  when  the  animal  stood  up, 
it  would  be  instantly  indicated  and  the  time  could  be  recorded.  Time 
records  of  these  changes  of  position  were  kept  throughout  the  day,  and  in 
fasting  experiments  throughout  the  night  also.  These  records  give  informa¬ 
tion  not  only  of  the  number  of  changes  from  standing  to  lying  and  vice 


BODY  MEASUREMENTS  AND  PHYSIOLOGICAL  FUNCTIONS  135 

versa,  but  likewise  of  the  total  amount  of  time  in  the  24  hours  that  the  ani¬ 
mals  were,  respectively,  standing  or  lying.  The  records- are  not  complete, 
however,  with  regard  to  this  latter  phase  of  the  observations,  for  such  records 
involve  continuous  observations  for  24  hours  throughout  the  entire  fast, 
and  the  pressure  of  other  work  occasionally  introduced  lapses  in  these 
records.  The  general  picture,  however,  indicates  that  the  animals  had  a 
tendency  to  lie  down  for  a  longer  time  as  the  fast  progressed.  Indeed,  in 
all  cases  the  fasting  steers  exhibited  the  same  tendency  to  conservation  of 
energy  as  was  noted  with  the  steers  on  undernutrition.  They  became  more 
quiet  and  inert  in  their  muscular  exertion  and  spent  a  larger  proportion 
of  the  time  lying  down  and  for  much  longer  periods  at  a  time  than  when 
on  feed.  Armsby  and  his  associates  have  been  wont  to  compute  the  24-hour 
metabolism  of  their  animals  on  the  basis  that  the  animal  spent  12  hours 
standing  and  12  hours  lying.  These  times  represent  the  average  times 
presumably  with  animals  on  feed.  These  fasting  steers,  however,  more 
commonly  spent  14  to  15  hours  instead  of  12  hours  in  the  lying  position. 
Minor  muscular  activities  also  affect  the  metabolism  considerably.  In 
the  respiration  chamber  such  minor  muscular  activity  was  graphically 
recorded  by  means  of  the  kymograph.®  The  kymograph  records  show  con¬ 
clusively  that  the  degree  of  activity  decreased  as  the  fast  progressed.  The 
activity  for  the  most  part  consisted  in  a  shifting  in  the  weight  of  the 
animal’s  position,  usually  with  a  remarkable  degree  of  regularity.  The 
time  elapsing  between  these  shifts  in  weight  gradually  lengthened  as  the 
fast  progressed.  In  the  long  fast  of  14  days  steer  D  invariably  showed  a 
somewhat  greater  activity  than  steer  C.  There  was  not  much  difference 
in  the  number  of  times  that  the  animals  stood  up  and  lay  down,  i.  e.,  the 
actual  number  of  times  that  they  shifted  their  position  was  not  greatly 
altered,  but  they  remained  down  for  a  longer  time. 

Salivation — After  the  second  day  of  fasting,  steer  D  almost  invariably 
began  salivation,  sometimes  rather  profusely,  and  continued  to  salivate 
up  to  the  fifth  day,  but  the  salivation  had  gradually  ceased  by  the  seventh 
day.  The  fact  that  none  of  the  other  three  fasting  steers  ever  exhibited 
this  trait  showed  that  this  was  an  individual  characteristic.  Obviously 
the  salivation  of  steer  D  was  somehow  associated  with  lack  of  food,  but 
the  absence  of  other  manifestations  suggesting  a  craving  for  food  implied 
that  the  salivation  was  probably  induced  in  part  by  the  condition  of  his 
teeth,  as  is  so  commonly  the  case  in  horses. 

Rumination — After  the  second  day  rumination  practically  ceased, 
although  there  were  occasional  evidences  of  it.  For  example,  no  rumination 
was  recorded  after  the  fourth  day,  except  in  the  10-day  fast  in  January, 
when  steer  D  apparently  showed  evidences  of  rumination.  On  the  whole, 
rumination  persisted  somewhat  longer  during  fasts  following  feeding  with 
dry  rations,  having  hay  for  a  basis,  than  it  did  during  fasts  after  grass 
feeding.  This  would  naturally  be  expected,  as  it  would  probably  take  a 
longer  time  to  saturate  and  prepare  hay  thoroughly  for  rumination. 

Behavior  during  refeeding  after  fast— Close  observation  of  the  behavior 
during  the  refeeding  period  after  the  fast  thoroughly  corroborates  the 


“  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  54. 


136 


METABOLISM  OF  THE  FASTING  STEER 


deductions  drawn  from  their  behavior  during  fasting.  Frequently  only 
hay  was  given  for  the  first  feed,  on  the  assumption  that  it  would  be  better 
at  the  start  to  supply  bulk  rather  than  highly  concentrated  matter.  When 
the  first  hay  feed  was  given  after  a  fast  of  5  or  more  days,  the  steers 
consumed  the  feed  in  an  indifferent  manner,  eating  intermittently  and 
slowly,  showing  no  signs  of  avidity  or  eagerness,  as  one  might  suppose. 
After  these  longer  fasts  their  capacity  or  desire  for  any  material  amount 
of  bulk  in  the  form  of  hay  was  apparently  limited,  as  they  usually  con¬ 
sumed  less  than  2  kg.  in  their  first  feed  and,  when  only  hay  was  fed,  from 
4  to  7  days  would  elapse  before  they  would  again  clean  up  a  ration  of  hay 
approximating  normal  maintenance.  In  those  cases  where  1,000  grams  of 
a  concentrated  meal  mixture  (equal  parts  by  weight  of  linseed  meal,  corn 
meal,  and  wheat  bran)  were  given,  the  meal  was  cleaned  up  in  15  minutes, 
which  was  still  a  much  longer  time  than  the  steers  required  for  this  amount 
under  ordinary  conditions  of  feeding.  When  the  animals  were  refed  on 
both  hay  and  meal,  their  appearance  would  improve  within  2  or  3  days, 
as  the  paunch  again  became  distended  and  the  hair  smoothed  down.  Like¬ 
wise  they  would  become  more  energetic,  and  in  a  week  or  less  they  would 
behave  and  appear  much  the  same  as  before  the  fast. 

General  Appearance 

In  all  fasts  the  first  visible  effect  of  the  lack  of  food  is  the  shrinking 
of  the  body  at  the  paunch.  In  the  fasts  of  from  2  to  5  days  this  shrinking 
in  size  was  confined  largely  to  the  region  of  the  paunch,  but  toward  the 
end  of  the  two  10-day  and  the  two  14-day  fasts  a  pronounced  shrinking  or 
sinking  in  at  the  flanks  also  became  apparent.  The  shrinkage  at  the  paunch 
was  most  marked  during  the  first  2  or  3  days,  corresponding  closely  to 
the  quantitative  rate  in  loss  of  solid  excreta  and  water  of  fill.  After  the 
fasts  which  did  not  exceed  5  to  7  days  in  length,  this  shrinking  in  the  size 
of  the  body  apparently  was  repaired  wuthin  a  week,  when  the  animals  had 
again  acquired  the  capacity  to  consume  a  full  ration  of  hay  and  a  normal 
complement  of  water. 

Condition  of  flesh — Nothing  is  so  important  to  the  experienced  stockman 
in  estimating  the  state  of  flesh  of  an  animal  as  is  visual  appraisal.  Weight, 
length,  or  girth  does  not  so  perfectly  express  to  him  the  true  condition  of 
flesh  of  the  animal.  Such  personal  appraisal  was,  however,  in  the  case 
of  these  steers,  supplemented  by  standard  measurements  of  lengths  and 
girths.  As  a  result  of  the  fasts  of  these  four  animals  there  was  no  visible 
indication  of  any  loss  in  flesh,  even  after  the  10-day  and  the  14-day  fasts, 
the  thighs  and  hind  quarters  generally  appearing  as  plump  as  before  the 
fast.  This  impression  was  also  obtained  from  “handling”®  or  feeling  the 
flesh  over  the  ribs,  a  butcher’s  procedure.  Although  both  steers  C  and  D 
were  extremely  gaunt  at  the  end  of  the  10-day  and  the  14-day  fasts,  Pro¬ 
fessor  McNutt,  of  the  Department  of  Animal  Husbandry  of  New  Hampshire 
College,  commented  on  their  appearance  as  follows: 

°  “Handling”  is  a  general  expression  used  by  butchers  and  livestock  men  generally  to  indicate 
thickness  and  quality  of  flesh. 


BODY  MEASUREMENTS  AND  PHYSIOLOGICAL  FUNCTIONS 


137 


“The  steers  are  in  good  condition,  considering  the  length  of  the  fast. 
They  have  apparently  lost  very  little  flesh  and  still  handle  well,  but  they 
have  undergone  considerable  shrinkage  due  to  loss  of  fill.  I  have  seen  cattle 
undergo  greater  shrinkage  in  a  3-day  shipment  on  cars  than  these  two 
steers  show.” 

Skin  and  hair — When  animals  in  good  flesh  are  well  nourished,  as  was 
the  case  previous  to  all  but  those  fasts  following  submaintenance  feeding, 
the  hair  is  soft,  fairly  glossy,  and  lies  flat  on  the  body,  giving  the  impression 
of  sleekness.  The  skin  is  soft,  pliant,  and  elastic  to  the  touch  or  manipula¬ 
tion.  Close  daily  observation  and  handling  or  feeling  of  skin  and  hair 
throughout  each  fast  indicated  that  the  hair  was  particularly  sensitive  to 
radical  changes  in  food-supply,  reacting  much  more  quickly  to  lack  of 
nourishment  than  was  true  of  the  skin.  Usually  by  the  second  or  third 
day  of  fasting  the  hair  began  to  lose  its  sleekness  and  bristled  out  more 
from  the  body,  having  a  dusty  appearance,  and  after  10  or  more  days  of 
fasting  it  became  somewhat  harsh  or  dry  to  the  touch.®  During  the  10-day 
and  the  14-day  fasts  considerable  shedding  also  took  place,  but  since  both 
of  these  fasts  occurred  during  the  spring  of  the  year,  the  cause  must  have 
been  at  least  partially  seasonal.  No  particular  effect  on  the  skin  was 
observable,  even  after  5  days  of  fasting,  but  at  the  end  of  the  10-day  and 
14-day  fasts,  probably  because  of  a  lack  of  replacement  of  fat  in  and 
more  particularly  under  it,  the  skin  seemed  to  become  drier  and  harder 
and  consequently  to  shrink,  so  that  it  adhered  more  tightly. 

Heart-Rate 

The  heart-rate  is  a  reasonably  good  index  of  the  general  metabolic  level. 
Extraordinarily  low  rates  have  been  previously  reported  for  steers  on 
submaintenance  rations,6  20  beats  per  minute  being  noted  in  the  case  of 
one  steer.  Since  simultaneously  with  the  low  heart-rate  there  was  a  greatly 
lowered  “standard  metabolism”  (see  p.  228),  it  can  be  seen  that  with  these 
animals,  as  with  humans,  variations  in  heart-rate  reflect  approximately,  at 
least,  the  metabolic  level.  The  importance  of  recording  heart-rates  in 
studies  with  steers  is  here  strongly  emphasized,  as  this  relationship  between 
heart-rate  and  metabolic  activity  is  so  prominent.  The  technique,  how¬ 
ever,  is  by  no  means  simple.  Accurate  determinations  of  representative 
heart-rates,  as  well  as  live  weights,  can  be  secured  only  with  the  greatest 
patience  and  care.  They  should  be  obtained  by  a  regular  attendant  and 
under  conditions  when  the  animal  is  placid  or  quiet  and  has  not  been 
unduly  excited.  The  animal  should  also  not  be  ruminating  throughout  the 
entire  time  of  counting  the  heart-rate,  since  rumination  increases  heart 
activity.  The  best  results  so  far  have  been  obtained  by  use  of  a  stethoscope 
placed  over  the  heart  of  the  animal.  It  is  not  at  all  unlikely  that  electro¬ 
cardiograms  might  be  secured  by  attaching  simple,  wet  electrodes  to  the 
legs,  making  the  electrodes  a  part  of  the  regular  harness.  Such  an  arrange¬ 
ment  would  be  ideal  and  probably  would  give  much  more  normal,  uncom- 

°  The  appearance  of  these  changes  depends  of  course  on  the  physical  conditions  in  which  the 
animals  start  fasting. 

b  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  193. 


138 


METABOLISM  OF  THE  FASTING  STEER 


Table  35. — Heart-rates  per  minute  of  steers  C  and  D,  on  feed  and  fasting 


Date 

Days 

fasting 

Steer  C 

Steer  D 

2  p.  m. 

4  p.  m. 

6  to 
7h30m 
a.  m. 

2  p.  m. 

4  p.  m. 

6  to 
7h30m 
a.  m. 

1921 

Dec.  3  to  5,  incl . 

49 

52 

42 

52 

55 

51 

Dec.  6—  7 . 

1 

144 

140 

44 

144 

48 

48 

7—  8 . 

2 

» 32 

36 

136 

36 

Dec.  8—  9 . 

3 

32 

36 

34 

36 

32 

40 

4 

32 

132 

36 

42 

Dec  10-11  . 

5 

38 

36 

38 

42 

1922 

Jan.  1  to  3,  incl . 

68 

61 

60 

70 

63 

64 

Jan.  4—  5 . 

1 

*64 

2  72 

*48 

172 

2  68 

152 

Jan.  5—  6 . 

2 

48 

60 

i38 

48 

148 

140 

Jan.  6—  7 . 

3 

136 

136 

138 

140 

40 

i36 

Jan.  7—  8 . 

4 

36 

136 

136 

40 

40 

‘38 

Jan.  8—  9 . 

5 

40 

136 

138 

138 

136 

‘36 

Jan.  9—10 . 

6 

34 

132 

38 

136 

‘38 

36 

Jan.  10-11 . 

7 

*  30 

32 

36 

132 

*36 

38 

Jan.  11-12 . 

8 

132 

‘28 

130 

36 

32 

38 

Jan.  12-13 . 

9 

36 

128 

34 

36 

30 

i36 

Jan.  13-14 . 

10 

128 

28 

38 

128 

134 

i27 

Apr.  14  to  16,  incl . 

57 

56 

51 

60 

61 

60 

Apr.  17-18.. . 

1 

60 

42 

»62 

54 

50 

Apr.  18-19 . 

2 

42 

52 

38 

140 

36 

Apr.  19—20 . 

3 

36 

132 

38 

136 

40 

Apr.  20—21 . 

4 

132 

1 30 

38 

1  34 

40 

Apr.  21-22 . 

5 

38 

36 

34 

42 

30 

Apr.  22—23 . 

6 

37 

1  32 

30 

42 

38 

Apr.  23-24 . 

7 

36 

34 

30 

40 

36 

30 

Apr.  24-25 . 

8 

3  40 

36 

32 

36 

40 

134 

Apr.  25-26 . 

9 

30 

130 

34 

38 

132 

138 

Apr.  26-27 . 

10 

3  44 

136 

132 

40 

48 

» 36 

Apr.  27—28 . 

11 

32 

36 

130 

40 

32 

132 

Apr.  28—29 . 

12 

30 

32 

32 

3  36 

38 

132 

13 

3  38 

128 

32 

32 

34 

Apr.  30-May  1 . 

14 

30 

134 

30 

32 

134 

132 

May  29  to  31,  incl . 

63 

61 

55 

71 

68 

65 

Juno  1—  2 . 

1 

156 

40 

164 

60 

54 

June  2—  3 . 

2 

44 

48 

140 

54 

140 

June  3—  4 . 

3 

144 

2  44 

3  44 

52 

3  48 

June  4—  5 . 

4 

34 

38 

32 

44 

42 

44 

June  5—  6 . 

5 

38 

136 

34 

48 

46 

Jiitia  6—  7 . 

6 

48 

2  33 

32 

Nov.  6  to  7 . 

1 

148 

*48 

Nov.  7-  8 . 

2 

44 

40 

1  38 

48 

1  40 

Nov.  8—  9 . 

3 

40 

3  48 

44 

48 

3  52 

Nov.  9—10 . 

4 

40 

48 

40 

48 

52 

Nov.  10-11 . 

5 

40 

38 

40 

i48 

46 

Nov.  11-12 . 

6 

138 

136 

136 

144 

142 

Nov.  12-13 . 

7 

36 

38 

36 

46 

42 

40 

Nov.  13-14 . 

8 

38 

36 

36 

42 

138 

40 

Nov.  14—15 . 

9 

136 

134 

38 

Nov.  15—16 . 

10 

36 

40 

36 

1  Lying. 


2  Lying  and  ruminating. 


3  Just  up. 


BODY  MEASUREMENTS  AND  PHYSIOLOGICAL  FUNCTIONS  139 


Table  35. — Heart-rates  per  minute  of  steers  C  and  D,  on  feed  and  fasting — Continued 


Date 

Days 

fasting 

Steer  C 

Steer  D 

2  p.  m. 

4  p.  m. 

6  to 
7h30m 
a.  m. 

2  p.  m. 

4  p.  m. 

6  to 
7h30m 
a.  m. 

1923 

Nov.  1  to  3,  incl . 

61 

69 

Nov.  4-  5 . 

1 

4  52 

Nov.  5—  6 . 

2 

48 

60 

Nov.  6-  7 . 

3 

46 

48 

44 

72 

52 

Nov.  7-8 . 

4 

136 

42 

8  48 

1 56 

8  56 

Nov.  8—  9 . 

5 

136 

42 

8  40 

52 

8  56 

Nov.  9—10 . 

6 

36 

36 

1 34 

1924 

Feb.  29  to  Mar.  2,  incl. . . 

35 

37 

35 

46 

49 

46 

Mar.  3-  4 . 

1 

34 

34 

36 

48 

48 

48 

Mar.  4—  5 . 

2 

32 

30 

30 

44 

36 

Mar.  5—  6 . 

3 

126 

28 

8  40 

132 

36 

36 

Mar.  6-  7 . 

4 

28 

26 

*28 

32 

34 

36 

Mar.  7-  8 . 

5 

26 

124 

28 

36 

48 

8  48 

Mar.  8—  9 . 

6 

‘26 

1 30 

124 

‘40 

1 36 

Mar.  9—10 . 

7 

30 

30 

25 

8  50 

132 

‘38 

Mar.  10-11 . 

8 

126 

26 

1 28 

34 

136 

Mar.  11-12 . 

9 

28 

*24 

30 

34 

Mar.  12-13 . 

10 

1 26 

126 

34 

1  Lying.  *  Just  up.  4  Taken  at  8h30m  a.  m. 


plicated  results,  but  this  method  has  not  as  yet  been  tested.  Owing  to  the 
much  disputed  quantitative  differences  between  the  metabolism  of  an 
animal  in  the  lying  and  standing  positions,  heart-rates  recorded  under 
these  conditions  should  be  studied  more  thoroughly.  Certain  technical 
difficulties  in  securing  the  heart-rate  with  the  animal  in  the  lying  position 
are  not  easily  overcome,  but  probably  electrocardiograms  under  these 
conditions  will  be  of  much  assistance  in  throwing  light  on  this  problem. 

Colin0  states  that  the  average  heart-rate  of  the  steer  is  from  45  to  50 
beats  per  minute,  as  shown  by  a  large  number  of  observations  by  veteri¬ 
narians.  Knoll,* 6  in  Ellenberger’s  laboratory  at  Dresden,  found  that  the 
heart-rate  of  these  animals  varied  between  36  and  102  beats  per  minute, 
being  on  the  average  70  beats. 

In  connection  with  the  fasts  of  5  to  14  days  the  heart-rates  per  minute 
of  all  four  of  our  steers  were  determined  on  most  of  the  fasting  days  and 
in  the  feeding-periods  preceding  the  fasts.  Usually  they  were  determined 
at  2  p.  m.,  4  p.  m.,  and  some  time  between^  6  and  7h  30m  a.  m.  The  data 
secured  on  each  of  the  fasting  days,  together  with  the  average  values  for 
3  days  on  food  preceding  each  fast,  are  recorded  in  Tables  35  and  36.  In 
these  tables  special  note  is  made  of  the  instances  when  the  animal  was 
lying,  ruminating,  or  had  just  stood  up  at  the  time  the  heart-rate  was 

°  Colin,  Trait6  de  Physiologie  Comparee  des  Animaux,  3d  ed.,  Paris,  1888,  2,  p.  476. 

6  Knoll,  Untersuchungen  iiber  die  normale  Pulsfrequenz  der  Rinder  und  Schweine  nebst  ver- 
gleichenden  physiologischen  kritischen  Studien  iiber  die  normale  Pulsfrequenz  des  Menschen  und 
der  Haussaugetiere.  Inaug.  Diss.,  Zurich,  1911,  p.  40. 


140 


METABOLISM  OF  THE  FASTING  STEER 


Table  36. — Heart-rates  per  minute  of  steers  E  and  F,  on  feed  and  fasting 


Date 

(1924) 

Days 

fasting 

Steer  E 

Steer  F 

2  p.  m. 

4  p.  m. 

7h30m 
a.  m. 

2  p.  m. 

4  p.  m. 

7h30m 
a.  m. 

Feb.  9  to  11,  incl . 

45 

44 

36 

46 

43 

36 

Feb.  12-13 . . 

1 

38 

36 

42 

40 

48 

44 

48 

Feb.  13-14 . 

2 

48 

36 

1 40 

44 

36 

Feb.  14-15 . 

3 

2  34 

36 

34 

36 

36 

36 

Feb.  15-16 . 

4 

2  34 

1 48 

36 

38 

36 

32 

Feb.  16-17 . 

5 

34 

2  36 

36 

40 

34 

2  34 

Feb.  17-18 . 

6 

36 

36 

36 

1  Just  up.  2  Lying. 


observed,  for  such  factors  might  have  considerable  influence  on  the 
heart-rate. 

Attention  is  first  called  to  the  average  heart-rates  in  the  food-periods 
prior  to  the  fasting  experiments.  In  the  case  of  steer  C,  in  December  1921, 
heart-rates  of  49,  52,  and  42  were  noted.  In  January  1922,  about  a  month 
later,  considerably  higher  rates  of  68,  61,  and  60  were  found.  In  April 
1922,  the  values  are  57,  56,  and  51,  about  intermediate  between  the  Decem¬ 
ber  and  January  values.  In  May  the  rate  has  again  risen  to  63,  61,  and  55, 
but  the  most  striking  change  is  during  the  submaintenance  period  in 
February,  when  the  values  were  35,  37,  and  35.  Essentially  the  same 
picture  is  shown  with  steer  D,  although  his  heart-rate  tends  in  general  to 
be  slightly  higher  than  that  of  steer  C.  Indeed,  even  on  submaintenance 
rations  his  heart-rate  is  pronouncedly  higher. 

Fasting  results  in  an  almost  continuous  fall  in  the  heart-rate,  noticeable 
at  practically  all  three  times  of  observation.  The  minimum  rate  noted 
with  steer  C  is  24  beats  per  minute,  which  was  found  on  three  different 
occasions  in  the  fast  following  submaintenance  feeding  in  March  1924. 
The  minimum  rate  noted  with  steer  D  was,  singularly  enough,  not  during 
the  fast  following  submaintenance  feeding,  but  during  the  fast  in  January 
1922,  when  it  was  28  and  27  beats  per  minute  on  the  last  day.  The  mini¬ 
mum  rates  were  usually  noted  when  the  animal  was  lying.  In  the  longest 
fast,  from  April  14  to  May  1,  the  heart-rates  fall  off  so  that  they  are  almost 
half  of  what  they  were  on  the  prefasting  feed-level.  In  the  fast  at  the 
submaintenance  level  the  fall  is  pronounced  with  steer  C,  but  by  no  means 
so  sharply  marked  as  with  steer  D. 

In  the  fasting  experiments  with  steers  E  and  F,  of  5  and  6  days  respec¬ 
tively,  the  heart-rates  of  steer  E  prior  to  fasting  were  45  beats  per  minute 
at  2  p.  m.,  44  beats  at  4  p.  m.,  and  36  beats  at  7h  30m  a.  m.  Almost  exactly 
the  same  values  were  found  with  steer  F.  These  animals  began  fasting 
after  a  long  period  on  submaintenance  rations.  The  minimum  heart-rate 
of  steer  E  wTas  34  beats,  a  rate  which  was  noted  at  least  four  times  toward 
the  end  of  the  fast.  With  steer  F  a  low  rate  of  34  beats  was  also  noted  on 
two  occasions,  but  the  minimum  rate  was  32  beats  at  7h  30ra  a.  m.  on  the 
fourth  day.  The  picture  is  essentially  the  same  with  both  animals  and 


BODY  MEASUREMENTS  AND  PHYSIOLOGICAL  FUNCTIONS  141 

is  in  conformity  with  the  picture  shown  by  steers  C  and  D,  that  is,  a 
distinct  falling  off  in  the  heart-rate  as  the  fasting  progresses. 

The  relationship  between  the  heart-rate  and  the  metabolism,  a  relation¬ 
ship  which  has  frequently  been  pointed  out  in  earlier  publications  from 
the  Nutrition  Laboratory,  is  strikingly  shown  in  the  series  of  4-day  experi¬ 
ments  with  steers  E  and  F  in  1924-25.  The  heart-rate  was  not  determined 
while  the  animal  was  inside  the  respiration  chamber,  but  it  was  determined 
twice  a  day  for  at  least  a  week  prior  to  each  respiration  experiment.  Thus, 
the  heart-rate  of  steer  E,  when  on  a  maintenance  ration  of  7  kg.  of  hay, 
either  timothy  or  alfalfa,  was  not  far  from  46  to  54  beats  per  minute,  the 
higher  values  being  observed  at  the  low  environmental  temperature  and 
with  the  alfalfa  hay.  Preceding  the  submaintenance  experiments  with 
timothy  hay,  as  low  a  value  as  33  beats  was  found  prior  to  January  13, 
1925.  The  effect  of  the  cold  environmental  temperature  and  submainte¬ 
nance  feeding  on  timothy  hay  prior  to  February  2,  1925,  is  reflected  in  a 
higher  heart-rate  of  41  beats,  as  compared  to  33  beats  in  the  earlier  sub¬ 
maintenance  experiment.  When  alfalfa  hay  was  fed,  the  heart-rate  fell, 
from  approximately  50  beats  on  the  maintenance  level  to  32  beats  on  the 
submaintenance  level. 

With  steer  F  the  picture  is  almost  identically  the  same.  With  the  mainte¬ 
nance  ration  of  timothy  hay  the  heart-rate  ranged  from  45  to  50  beats  per 
minute.  On  the  submaintenance  ration  of  timothy  hay  it  was  34  to  35 
beats.  In  both  instances  the  environmental  temperature  was  about  22°  C. 
With  a  lower  temperature  and  a  submaintenance  ration  of  timothy  hay 
the  heart-rate  was  a  little  higher,  42  beats.  On  the  maintenance  ration 
of  alfalfa  hay  the  rate  was  46  to  52  beats  and  on  the  submaintenance  ration 
of  alfalfa  hay  it  fell  to  36  beats,  although  the  environmental  temperature 
remained  the  same,  i.  e.,  about  22°  C.  The  state  of  nutrition  evidently  has 
a  pronounced  effect  on  the  heart-rate,  and  there  is  a  strong  suggestion  of 
a  more  rapid  heart-rate  with  a  lower  environmental  temperature. 

Respiration-Rate 

The  extremely  high  respiration-rates  commonly  noted  in  very  fat  animals 
suggested  that  records  of  the  respiration-rate  should  be  made  a  part  of 
the  daily  observations,  and  accordingly  during  the  winter  of  1924  and 
1925  an  attempt  was  made  to  secure  regular  records  of  this  important 
physiological  factor.  It  was  found  even  more  difficult  to  secure  reliable 
records  of  the  rate  of  respiration  than  of  the  heart-beat.  The  extraneous 
gross  movements  of  these  ruminants  are  so  frequent  that  a  kymograph 
curve  can  not  properly  record  the  respirations  for  more  than  a  few  seconds 
at  a  time.  It  is  practically  impossible  for  any  one  other  than  the  regular 
attendant  to  secure  such  data  without  extraordinary  precautions,  and  care 
should  be  taken  that  the  animal  is  not  apprehensive,  has  undergone  no 
physical  exertion,  and  is  not  eating  or  ruminating  at  the  time.  The  appli¬ 
cation  of  a  pneumograph  about  the  thorax  as  a  part  of  the  regular  harness, 
a  method  so  successfully  used  by  Pott,°  has  not  thus  far  been  attempted 
in  our  research.  We  have  attempted  to  count  the  respirations  by  watching 


°  Pott,  Ohio  Journ.  SoL,  1918,  18,  p.  129. 


142 


METABOLISM  OF  THE  FASTING  STEER 


the  movements  of  the  chest,  and,  in  some  instances,  by  placing  the  hand 
over  the  nostrils.  The  animals  seemed  to  be  extraordinarily  susceptible  to 
slight  changes  in  environment,  so  that  the  respiration-rates  can  not  be 
discussed  except  with  greatest  reserve.  Exercising  every  care,  but  not 
employing  the  pneumograph,  we  secured  a  few  observations  during  fasting 
days,  and  these  are  recorded  in  Table  37.  The  data  are  so  few  that  discus¬ 
sion  of  them  is  hardly  justified.  It  would  appear,  however,  as  if  during 
fasting  the  respiration-rate  of  these  animals  was  not  far  from  9  or  10 
respirations  per  minute.  It  is  obvious  that  much  remains  to  be  done  in 
studying  the  respiration-rate  of  steers,  and  undoubtedly  the  pneumograph 
must  replace  any  manual  or  visual  counting. 


Table  37. — Respiration-rates  of  fasting  steers 


Steer  and  date 
(1924) 

Days 

fasting 

Number 

of 

records 

Respiration- 

rate 

per  minute 
(average) 

Steer  C: 

Mar.  4 . 

2 

4 

10 

Mar.  5 . 

3 

5 

11 

Mar.  12 . 

10 

5 

9 

Steer  D: 

Mar.  4 . 

2 

3 

9 

Mar.  11 . 

9 

2 

9 

Steer  F: 

Feb.  17 . 

6 

2 

9 

Rectal  Temperature 

The  profound  changes  noted  during  fasting  in  the  body-weight,  the 
circulatory  activity  (as  indicated  by  the  heart-rate),  and  the  general 
condition  of  the  animal  (as  exhibited  by  the  external  appearance,  and 
the  decrease  in  metabolism  and  in  muscular  activity),  all  suggested  that 
fasting  might  have  an  influence  upon  the  rectal  temperature.  Hence, 
throughout  the  entire  research,  rectal  temperatures  were  recorded  at  specific 
hours  of  the  day  (usually  at  2  p.  m.,  4  p.  m.,  and  6  or  T^O^a.  m.).  A 
veterinarian’s  thermometer  was  used,  and  almost  invariably  the  same 
observer  made  the  readings,  due  precautions  being  taken  as  to  the  length 
of  time  that  the  thermometer  was  inserted  and  that  the  depth  of  insertion 
be  10  cm.  With  stall-fed  animals  the  diurnal  variation  in  temperature 
should  be  studied,  preferably  with  a  resistance  thermometer  or  a  thermo¬ 
electric  element,  and  frequent  observations  should  be  made.  Thus  far, 
however,  no  attempt  has  been  made  to  use  such  a  technique. 

Space  will  not  permit  of  publishing  the  long  series  of  observations  which 
were  secured  on  the  rectal  temperature  of  these  steers.  A  careful  exami¬ 
nation  of  the  data  shows  that  the  two  animals,  C  and  D,  had  almost  inva¬ 
riably  the  same  rectal  temperature,  which  averaged  not  far  from  38.2°  C. 
In  general,  the  highest  temperatures  were  noted  at  2  p.  m.  and  the  lowest 
at  6  a.  m.,  suggesting  a  diurnal  rhythm.  During  the  fasts  the  rectal  tem¬ 
perature  on  the  average  was  but  two  or  three  tenths  of  a  degree  higher 


BODY  MEASUREMENTS  AND  PHYSIOLOGICAL  FUNCTIONS  143 

on  the  first  day  than  on  succeeding  days,  but  after  the  second  day  remained 
reasonably  uniform  throughout  the  entire  fast,  irrespective  of  its  length. 

The  highest  rectal  temperature  observed  during  the  fasting  days  was 
39.2°  C.  on  January  4,  1922,  at  2  p.  m.,  with  both  steers  C  and  D.  The 
lowest  temperature  observed  was  37.2°  C.  This  temperature  was  noted  in 
a  number  of  instances,  namely,  at  4  p.  m.,  November  8,  1923,  with  steer  C; 
at  7  a.  m.,  November  9,  1923,  with  both  steers  C  and  D;  and  at  4  p.  m., 
March  4,  1924,  with  steer  C.  The  rectal  temperature  was  essentially  the 
same  throughout  all  the  fasts,  irrespective  of  the  previous  state  of  nutrition 
or  the  character  of  the  ration.  Thus,  in  the  fast  following  submaintenance 
feeding  in  March  1924,  the  rectal  temperature  was  on  the  average  only 
one-tenth  of  a  degree  lower  than  in  the  other  fasts. 

Steers  E  and  F,  during  their  fast  in  February  1924,  following  submainte¬ 
nance  feeding,  had  in  general  a  slightly  lower  rectal  temperature  than  steers 
C  and  D,  the  average  temperatures  ranging  from  38.1°  C.  on  the  second 
day  to  37.7°  C.  on  the  fifth  day. 

Examination  of  the  data  obtained  on  feeding  days,  to  determine  whether 
the  different  feed-levels  and  digestive  activity  possibly  have  an  influence 
upon  rectal  temperature,  indicates  that  the  temperature  was  usually  highest 
at  2  p.  m.,  but  in  practically  all  cases  the  range  in  temperature  was  within 
1°  or  1.5°  C.  The  barn  temperature  had  a  slight  effect,  for  on  the  warmer 
days  the  rectal  temperature  was  on  the  average  one  or  two  tenths  of  a 
degree  higher  than  on  the  colder  days.  It  would  thus  appear  as  if  prolonged 
fasting  resulted  in  no  material  disturbance  of  the  normal  rectal  temperature, 
which  was  singularly  unaffected  either  by  changes  in  feed-level  or  by 
changes  in  environmental  temperature. 

Skin  Temperature 

The  pronounced  change  in  heat-production  exhibited  by  these  animals 
when  fasting,  and  particularly  following  submaintenance  rations,  made  a 
study  of  skin  temperature  of  possible  interest.  During  the  March  1924 
fast  of  steers  C  and  D,  which  followed  a  submaintenance  ration,  the  skin 
temperature  was  measured  at  six  different  positions  on  the  body  on  the 
successive  days  of  the  fast.  In  these  measurements  the  thermo-electric 
method  was  employed,  which  has  been  so  extensively  used  with  humans 
at  the  Nutrition  Laboratory  and  which  was  used  to  a  slight  extent  in  the 
earlier  research  on  undernutrition  in  steers.0  The  difficulty  of  securing 
the  skin  temperature  of  an  animal  whose  skin  is  covered  with  hair  has  been 
pointed  out  frequently,  but  simply  for  purposes  of  comparison  these  meas¬ 
urements  were  made  over  the  hair,  that  is,  there  was  no  attempt  to  place 
the  thermo- junction  at  the  base  of  the  hair  next  to  the  skin.  In  an  earlier 
research®  the  skin  temperatures  of  12  steers  were  noted  on  one  day  only. 
Unfortunately,  the  environmental  temperature  was  not  recorded,  but  the 
evidence  was  that  it  was  high.  With  this  high  environmental  temperature 
the  average  skin  temperature  of  two  groups  of  steers  on  submaintenance 
rations  was  not  far  from  32.4°  C.  In  the  fasting  experiment  of  March 
1924,  the  environmental  temperature  ranged  from  14°  to  18.5°  C.  The 

0  Benedict,  Miles,  and  Johnson,  Proc.  Nat.  Acad.  Sci.,  1919,  5,  p.  218;  Benedict  and  Ritzman, 
Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  pp.  75,  181,  and  183. 


144 


METABOLISM  OF  THE  FASTING  STEER 


average  skin  temperature  of  steer  C  was  27.5°  C.  and  of  steer  D,  28.0°  C. 
There  was  a  slight  tendency  for  the  skin  temperature  to  decrease  as  the 
fast  progressed. 

It  is  clear  that  the  environmental  temperature  plays  a  large  role  in  such 
studies,  and  that  little  can  be  stated  until  fasting  experiments  are  made 
under  uniform  conditions  of  environmental  temperature.  No  evidence  is 
available  as  to  what  would  have  been  the  skin  temperature  of  an  animal 
on  full  feed  at  this  environmental  temperature.  The  fact  that  the  average 
skin  temperatures  noted  during  this  fast  were  nearly  4  or  5  degrees  below 
those  found  in  the  earlier  study  on  undemutrition  is  probably  in  large  part 
accounted  for  by  the  difference  in  the  environmental  temperature,  and  it 
is  reasonable  to  assume  that  the  fasting  per  se  or,  indeed,  the  fasting  and 
the  previous  submaintenance  ration,  were  without*  material  effect  upon  the 
skin  temperature.  This  finding  parallels  in  a  general  way  the  conclusion 
drawn  with  regard  to  the  rectal  temperature. 

GASEOUS  METABOLISM  AND  ENERGY  RELATIONSHIPS 
Metabolism  Measurements  Actually  Made  or  Computed 

As  the  best  index  of  the  total  metabolic  activity  of  a  living  organism 
physiologists  have  long  accepted  the  heat-production  and  its  accompanying 
gaseous  metabolism,  primarily  the  production  of  carbon  dioxide  and  the 
absorption  of  oxygen.  The  apparatus  at  Durham,  New  Hampshire,  was 
originally  designed  to  measure  only  the  carbon  dioxide  given  off  by  the 
animal  while  inside  the  chamber.  Subsequently  the  installation  of  the 
delicate  gas-analysis  apparatus  designed  by  Carpenter  (see  p.  33)  made 
possible  the  determination  of  the  respiratory  quotient,  and  from  these  two 
factors  the  actual  oxygen  consumption  and  the  heat-production  could  be 
computed. 

Methane — In  the  ruminant  another  gas  enters  into  the  gaseous  metab¬ 
olism,  for  as  a  consequence  of  the  prolonged  retention  of  food  residues  in  the 
intestinal  tract  there  are  extensive  fermentations  which  result  in  the  produc¬ 
tion  not  only  of  material  amounts  of  free  carbon  dioxide  but  of  methane.  In 
the  case  of  humans  and  most  carnivorous  and  omnivorous  animals,  methane 
is  rarely  present  in  measurable  amounts  and  it  is  ordinarily  disregarded 
in  metabolism  measurements.  Since  the  study  of  the  intestinal  fermenta¬ 
tion  has  given  rise  to  the  firm  conviction  that  the  methane  production  is  an 
index  of  the  digestive  activity,  the  determination  of  methane  has  acquired 
new  significance  in  metabolism  measurements.  In  most  of  our  earlier 
work  methane  determinations  were  impracticable.  The  extensive  train 
of  combustion  furnaces  and  purifying  devices  formerly  considered  essential 
for  such  determinations  were  too  complex  for  use  with  the  apparatus 
installed  at  Durham,  New  Hampshire,  as  this  apparatus  was  primarily 
designed  for  the  simplest  total  metabolism  measurement  with  ruminants, 
the  idea  being  not  to  have  it  too  complicated  or  elaborate  for  use  by  other 
experiment  stations.  On  a  visit  of  one  of  us  to  Copenhagen  a  device 
designed  by  Professor  Mpllgaard  for  the  analysis  and  determination  of 
methane  seemed  so  promising  that  Dr.  T.  M.  Carpenter,  of  the  Nutrition 


GASEOUS  METABOLISM  AND  ENERGY  RELATIONSHIPS  145 

Laboratory  staff,  made  a  special  visit  to  Professor  Mpllgaard’s  institute  in 
the  spring  of  1925,  and  on  his  return  to  America  he  so  modified  his  delicate 
gas-analysis  apparatus  (see  p.  33)  that  we  are  now  able  to  measure  the 
methane  production  accurately.  Up  to  the  time  of  completing  the  collection 
of  fasting  data  for  this  monograph,  however,  no  determinations  of  methane 
had  been  made.  Thanks  to  the  kindly  cooperative  spirit  of  Professor 
Armsby  in  checking  our  first  fasting  experiment  (which  he  helped  to  plan) 
by  subsequently  making  two  fasting  experiments  with  cows,  it  seemed 
justifiable  to  proceed  without  these  intricate  determinations  in  our  fasting 
experiments,  because  the  methane  investigations  in  Professor  Armsby’s 
laboratory  indicated  that  during  the  first  few  days  of  fasting  the  formation 
of  methane  falls  off  rapidly.0  It  is  of  importance  to  note  that  in  subsequent 
fasting  experiments  during  the  fall  and  winter  of  1925-26  our  methane  data 
confirm  fully  the  findings  of  Armsby  and  Braman,  indicating  that  there  is 
a  rapid  cessation  of  fermentative  activity  after  the  withdrawal  of  food. 
Our  own  determinations  of  methane  will  not  be  discussed  in  this  monograph, 
however,  as  they  do  not  apply  to  these  particular  fasting  experiments. 
The  value  of  methane  measurements  in  the  calculation  of  the  energy 
transformations  of  ruminants  has  been  pointed  out  by  Andersen* * * 6  and  such 
measurements  play  an  important  role  in  his  system  of  computing  the  heat- 
production  from  the  measured  oxygen  consumption  and  carbon-dioxide  pro¬ 
duction.  This  method  of  computing  the  heat-production  has  not  been 
employed  by  us  (see  p.  148). 

The  close  relationship  between  the  carbon-dioxide  production  and  the 
directly  determined  heat-production,  early  reported  by  Armsby  and  his 
associates,  convinced  us  that  the  direct  determination  of  the  carbon-dioxide 
production  alone  would  be  of  value  in  many  problems  of  animal  research, 
particularly  when  orientation  is  first  desired.  Stress  was  therefore  laid 
upon  the  measurement  of  the  carbon-dioxide  production,  and  provisions 
were  made  for  the  accurate  measurement  of  this  factor  in  each  experi¬ 
mental  period  of  our  research.  This  was  the  only  factor  determined  quan¬ 
titatively.  The  oxygen  consumption  was  measured  relatively  by  noting 
the  carbon-dioxide  increment  and  the  oxygen  decrement  in  the  ventilating 
air-current,  computing  therefrom  the  respiratory  quotient,  and  finally  cal¬ 
culating  the  oxygen  consumption  from  the  respiratory  quotient  and  the 
total  carbon-dioxide  production.  It  is  thus  seen  that  the  most  important 
measurement  enabled  by  the  apparatus  at  Durham,  New  Hampshire,  is 
that  of  the  carbon-dioxide  production.  During  fasting  experiments,  par¬ 
ticularly  after  the  first  day  or  two,  the  carbon-dioxide  production  is  an 
accurate  index  of  the  actual  heat-production.  The  reserve  of  carbohydrates 
in  the  food  and  body  glycogen  is  heavily  drawn  upon  during  the  first  few 
days  of  fasting,  and  thereafter  fat  combustion  predominates.  The  calorific 
value  of  carbon  dioxide  during  fat  combustion  is  essentially  constant,  and 
hence  under  fasting  conditions  this  gaseous  measurement  of  itself  is  an 
excellent  index  of  energy  transformations. 

“  Details  of  these  investigations  Professor  Armsby  kindly  submitted  to  us  in  correspondence, 

just  prior  to  his  untimely  death.  The  data  have  subsequently  been  published  by  Braman, 

Journ.  Biol.  Chem.,  1924,  60,  p.  85. 

6  Andersen,  K.  Vet.  og.  Landbohojsk.  (Copenhagen),  Aarsskr.,  1920,  p.  157;  ibid.,  Biochem. 
Zeitschr.,  1922,  130,  p.  143. 


146 


METABOLISM  OF  THE  FASTING  STEER 


The  relationship  between  the  volume  of  carbon  dioxide  produced  and 
the  volume  of  oxygen  consumed  indicates  the  nature  of  the  combustion  in 
the  body.  When  fats  exclusively  are  burned,  the  respiratory  quotient  is 
approximately  0.70.  Rarely  is  it  found  to  be  below  this,  and  such  quotients 
have  been  interpreted  as  indicating  the  possible  conversion  of  fat  into 
carbohydrate.  When  pure  carbohydrates  are  burned,  the  ratio  is  1.00, 
and  it  is  usually  assumed  that  a  respiratory  quotient  above  1.00  indicates 
the  transformation  of  carbohydrate  into  fat.  With  a  combustion  exclu¬ 
sively  of  carbohydrate  the  quotient  of  1.00  is  to  be  expected.  If  any  carbo¬ 
hydrate  is  converted  into  fat,  this  results  in  an  increased  liberation  of 
carbon  dioxide  and  raises  the  quotient.  It  is  highly  improbable  that  there 
is  a  sharply  defined  line  which  separates  a  combustion  exclusively  of 
carbohydrate  and  the  transformation  of  some  carbohydrate  into  fat,  even 
if  the  quotient  does  rise  above  1.00.  Thus,  our  colleague,  Dr.  T.  M. 
Carpenter,  is  convinced,  by  his  own  experiences  in  gas  analysis,  that  there 
may  be  a  conversion  of  considerable  carbohydrate  into  fat  when  the  respi¬ 
ratory  quotient  is  less  than  1.00.  Respiratory  quotients  over  1.00,  however, 
have  been  commonly  accepted  as  indicating  fat  formation  and  respiratory 
quotients  of  1.00  or  below  as  indicating  carbohydrate  combustion,  the 
intensity  of  which  depends  upon  the  proportion  of  carbohydrate  in  the 
combustion,  which  becomes  greater  the  nearer  the  respiratory  quotient  is 
to  1.00. 

In  lieu  of  direct  calorimetric  measurements  (the  apparatus  at  Durham 
not  being  designed  to  measure  heat  directly),  it  is  necessary  to  calculate 
the  heat-production  from  the  gaseous  exchange.  The  carbon-dioxide  deter¬ 
mination  alone  is  of  value,  particularly  when  the  heat  factors  of  Armsby 
and  his  associates  are  used.  The  relationships  between  heat-production  on 
the  one  hand,  and  carbon-dioxide  production  and  oxygen  consumption  on 
the  other  hand,  are  well  known.  Thus,  in  the  oxidation  of  the  several 
organic  substances  which  enter  into  the  metabolism  of  the  body,  notably 
carbohydrates,  proteins,  and  fats,  the  amount  of  heat  liberated  per  liter 
of  oxygen  absorbed  is  relatively  constant.  The  greatest  variations  in  the 
calorific  value  of  oxygen  exist  between  the  combustion  of  pure  fat  and 
the  combustion  of  pure  carbohydrates.  With  humans  it  has  been  found 
that  12  hours  after  the  last  meal,  provided  this  has  not  been  excessively 
rich  in  either  carbohydrate  or  protein,  the  respiratory  quotient  on  the 
average  is  0.82.  Under  these  conditions  the  oxygen  absorbed  has  an  energy 
equivalent  of  4.825  calories  per  liter,  and  is  an  accurate  measure  of  the 
energy  transformations.  With  ruminants  the  case  is  not  so  simple.  A 
respiratory  quotient  of  0.82  is  rarely  noted,  except  during  the  transition 
from  regular  feeding  to  a  fasting  condition.  Usually  ruminants  are  con¬ 
tinually  feeding  and  the  quotient  is  generally  1.00  or  slightly  above.  When 
feed  is  withheld  for  several  days,  the  quotient  rapidly  falls  to  not  far 
from  0.74  to  0.72.  Under  the  feeding  conditions  the  calorific  value  of 
oxygen  represents  a  pure  carbohydrate  combustion,  and  under  the  fasting 
conditions  almost  a  pure  fat  combustion.  Between  the  two  extremes  there 
is  a  difference  of  about  6  per  cent  in  the  calorific  value  of  a  liter  of  oxygen. 
The  corresponding  difference  in  the  calorific  value  of  carbon  dioxide  is 


GASEOUS  METABOLISM  AND  ENERGY  RELATIONSHIPS 


147 


approximately  30  per  cent.  Hence  the  determination  of  the  oxygen  con¬ 
sumption  per  se  places  energy  calculations  upon  a  much  more  accurate 
footing. 

Since  our  respiratory  technique  enabled  the  direct  determination  of  the 
carbon-dioxide  production  and  the  respiratory  quotient,  it  was  possible  to 
compute  the  heat-production  either  from  the  carbon-dioxide  production  or 
the  computed  oxygen  consumption.  From  the  actually  determined  heats 
of  combustion  of  the  various  nutrients,  such  as  proteins,  fats,  and  carbo¬ 
hydrates,  in  the  bomb  calorimeter,  and  from  a  comparison  of  the  measured 
energy  and  the  carbon-dioxide  production,  it  has  been  found  that  for 
each  gram  of  carbon  dioxide  produced  in  the  combustion  of  carbohydrate 
there  is  a  production  of  2.58  calories.  On  the  contrary,  when  fat  is  burned, 
approximately  3.4  calories  are  produced  for  each  gram  of  carbon  dioxide. 
The  difference  between  the  two  values  makes  it  seemingly  impossible  to 
use  carbon  dioxide  as  an  accurate  measure  of  the  heat-production  of 
animals,  except  under  conditions  where  the  character  of  the  combustion 
is  fairly  definitely  known,  as,  for  example,  during  prolonged  fasting. 

Due  to  the  foresight  of  Professor  H.  P.  Armsby,0  however,  a  large  number 
of  measurements  of  the  carbon-dioxide  production  and  the  heat-production 
of  large  ruminants  in  his  calorimeter  have  been  recorded,  and  the  actual 
ratio  between  the  carbon-dioxide  production  and  the  heat-production  has 
been  determined  for  different  animals  on  various  kinds  and  amounts  of 
feed.  Thus,  it  was  at  first  thought  that  this  relationship  could  be  computed 
with  a  good  degree  of  accuracy  by  the  equation  Y3  —  —0.0226a:  -f-  2.802,  in 
which  x  is  the  air-dry  weight  of  feed  in  grams  per  kilogram  of  live  weight, 
and  F3  is  the  measured  heat-production  per  kilogram  of  live  weight  divided 
by  the  grams  of  carbon  dioxide  produced  per  kilogram  of  live  weight. 

These  earlier  experiments  all  dealt  with  animals  which  had  been  given 
varying  amounts  of  feed.  A  subsequent  series  planned  by  Armsby  included 
fasting  experiments,  and  a  revision  of  his  earlier  tabulations  has  been 
published  by  one  of  Armsby’s  associates,  Braman,* 6  who  has  suggested  the 
modified  equation  Ya  =  — 0.02886x  -f-  2.883.  By  using  this  equation, 
Braman  has  computed  the  heat-production  from  the  carbon-dioxide  pro¬ 
duction  with  a  series  of  cows  which  had  been  fasting  from  1  to  8  days. 
Obviously,  in  such  instances  the  value  of  x  is  zero.  The  calculated  heat- 
production  is,  however,  invariably  lower  than  that  actually  measured,  and 
division  of  the  observed  heat-production  by  the  observed  carbon-dioxide 
production  of  these  fasting  cows  shows  that  the  calorific  value  of  carbon 
dioxide,  instead  of  being  2.883,  is  on  the  average  nearer  3.105.  In  the  first 
days  of  fasting,  however,  this  value  is  somewhat  different  than  in  the  later 
days. 

For  purposes  of  comparison  of  the  heat-production  as  computed  from 
the  carbon-dioxide  production  and  the  actually  determined  respiratory 
quotient  with  the  heat-production  as  computed  from  the  carbon  dioxide 
to  heat  ratio,  we  arbitrarily  used  the  factor  3.02  as  representing  the  calories 
per  gram  of  carbon  dioxide  during  the  first  24  hours  after  food,  the  factor 

°  Armsby,  FrieB,  and  Braman,  Proc.  Nat.  Acad.  Sci.,  1920,  6,  p.  263. 

6  Braman,  Journ.  Biol.  Chem.,  1924,  60,  p.  79. 


148 


METABOLISM  OF  THE  FASTING  STEER 


3.13  for  experiments  made  between  the  twenty-fifth  and  the  forty-eighth 
hours  after  food,  and  the  factor  3.20  for  experiments  made  more  than  48 
hours  after  food.  Since  the  heat-production  could  not  be  directly  deter¬ 
mined  in  our  apparatus,  we  were  confronted  with  the  alternative  of  com¬ 
puting  the  heat-production  from  the  carbon-dioxide  production  either  by 
means  of  the  revised  Armsby  factor  or  by  means  of  the  calorific  value  of 
carbon  dioxide  at  a  known  respiratory  quotient.  The  heat-production  of 
our  fasting  steers  was  accordingly  computed  for  every  experiment  made 
by  multiplying  the  measured  carbon-dioxide  production  (a)  by  the  above 
ratios  and  (6)  by  the  calorific  value  of  carbon  dioxide  at  the  respiratory 
quotient  actually  determined.  A  comparison  of  the  heat  values  as  com¬ 
puted  on  these  two  bases  shows  that  in  general  when  the  respiratory  quo¬ 
tient  is  not  far  from  0.82  the  agreement  in  the  two  methods  of  calculation 
is  close,  but  when,  as  is  frequently  the  case  in  fasting  experiments,  the 
respiratory  quotient  is  much  nearer  0.70,  the  heat-production  as  computed 
by  the  factor  obtained  from  Braman's  data  is  almost  invariably  about 
4  or  5  per  cent  lower  than  that  computed  from  the  calorific  value  of  carbon 
dioxide  at  the  known  respiratory  quotient.  When  the  respiratory  quotient 
is  above  0.82,  the  reverse  is  true,  the  Braman  factor  giving  higher  results 
than  the  calculations  from  the  respiratory  quotient  and  the  measured 
carbon-dioxide  production.  Since  the  Nutrition  Laboratory  has  numerous 
calorimetric  data  available  on  other  animals,  which  support  the  calcula¬ 
tions  of  the  heat-production  from  the  carbon-dioxide  production  and  the 
respiratory  quotient,  we  feel  more  confidence  in  this  latter  method  of 
computation.  Hence  this  method  has  been  employed  in  computing  the 
heat-production  in  all  instances  where  the  respiratory  quotient  is  1.00  or 
below. 

The  calorific  value  of  carbon  dioxide  has  been  well  established  for 
respiratory  quotients  between  0.70  and  1.00,°  and  varies  from  3.408  calories 
per  gram  with  a  respiratory  quotient  of  0.70  to  2.569  calories  per  gram 
with  a  respiratory  quotient  of  1.00.  There  is  still  much  discussion  as  to 
the  calorific  value  of  carbon  dioxide  and  oxygen  when  the  respiratory 
quotient  is  above  1.00,  a  situation  which  does  not  occur  in  fasting  experi¬ 
ments,  but  not  infrequently  occurs  in  feeding  experiments.  A  considerable 
amount  of  published  experimental  evidence* * 6  and,  indeed,  unpublished 
experiments  of  the  Nutrition  Laboratory  with  geese  and  with  a  pig  which 
are  also  available,  indicate  that  the  calorific  value  of  oxygen  at  a  respira¬ 
tory  quotient  above  1.00  is  not  essentially  different  from  that  at  1.00. 
Pending  further  and  more  elaborate  direct  determinations  of  the  calorific 
value  of  oxygen  at  different  respiratory  quotients,  therefore,  the  computa¬ 
tion  of  the  heat  values  reported  in  this  monograph  was  carried  out  as 
follows  in  all  cases  where  the  respiratory  quotient  was  over  1.00.  The 
amount  of  oxygen  actually  involved  in  the  metabolism  is  computed  from 
the  measured  carbon-dioxide  production  (converted  from  grams  to  liters) 

a  See  Benedict  and  Talbot,  Carnegie  Inst.  Wash.  Pub.  No.  201,  1914,  p.  29,  where  values  origi¬ 

nally  established  by  Zuntz  have  been  retabulated. 

6Rapport,  Weiss,  and  Csonka,  Journ.  Biol.  Chem.,  1924,  60,  p.  683;  Wierzuchowski  and  Ling, 
Journ.  Biol.  Chem.,  1925,  64,  p.  697. 


GASEOUS  METABOLISM  AND  ENERGY  RELATIONSHIPS  149 

and  the  determined  respiratory  quotient,  and  the  liters  of  oxygen  thus 
found  are  multiplied  by  the  factor  5.047,  the  calorific  value  of  a  liter  of 
oxygen  at  a  quotient  of  1.00. 

Under  conditions  where  carbohydrate  is  converted  into  fat  there  is  a 
splitting  off  of  carbon  dioxide  unaccompanied  by  the  absorption  of  oxygen, 
the  so-called  “atypical”  carbon  dioxide.  In  addition,  there  is  the  carbon 
dioxide  produced  by  fermentations  in  the  intestinal  tract,  and  this  produc¬ 
tion  is  not  accompanied  by  any  appreciable  absorption  of  oxygen.  Hence 
the  whole  situation,  particularly  with  ruminants,  is  complicated  by  these 
two  factors. 


Table  38  —Comparison  of  heat-production  calculated  by  Andersen  formula  and  from  measured 

oxygen  consumption 


M0llgaard 

experiment 

number 

Heat  produced  per  24  hours 
* 

Difference 

(a) 

Calculated  by 
Andersen 
formula 

(b) 

Calculated  from 
oxygen 
consumption1 

(c) 

Total 
(&>  <o) 

(d) 

Per  cent 
(-« x  I0°) 

cal. 

cal. 

cal. 

10 

8,431 

8,496 

+  65 

+0.77 

11 

10,505 

10,419 

-  86 

-0.82 

12 

12,854 

12,594 

-260 

-2.02 

14 

7,809 

7,853 

+  44 

+0.56 

15 

8,261 

8,288 

+  27 

+0.33 

16 

9,874 

9,761 

-113 

—  1.14 

17 

11,701 

11,405 

-296 

-2.53 

20 

8,471 

8,410 

-  61 

-0.72 

21 

10,098 

10,201 

+  103 

+  1.02 

22 

10,210 

10,069 

-141 

-1.38 

23 

11,690 

11,704 

+  14 

+0.12 

24 

12,413 

12,179 

-234 

-1.89 

25 

12,691 

12,569 

-122 

-0.96 

26 

13,143 

12,777 

-366 

-2.78 

27 

13,350 

13,227 

-123 

-0.92 

30 

9,197 

9,260 

+  63 

+0.69 

31 

9,946 

10,044 

+  98 

+0.99 

32 

10,802 

10,753 

-  49 

-0.45 

33 

11,813 

11,714 

-  99 

-0.84 

34 

12,235 

12,114 

-121 

-0.99 

35 

13,922 

13,702 

-220 

-1.58 

1  Assumed  that  each  liter  of  oxygen  is  equivalent  to  5.06  calories. 


In  this  connection,  a  study  of  M0llgaard’sa  data  obtained  upon  feeding 
ruminants  is  of  interest.  In  computing  the  heat-production  of  his  animals, 
M0llgaard  makes  use  of  the  clever  formula  devised  by  his  former  associate, 
A.  C.  Andersen.* * * 6  This  formula,  however,  involves  the  determination  of 
methane  and  the  nitrogen  in  urine,  as  well  as  the  gaseous  determination  of 
the  carbon-dioxide  production  and  the  oxygen  consumption.  From  unpub¬ 
lished  experiments  at  the  Nutrition  Laboratory  with  surfeit  feeding  of 

0  M0llgaard,  Om  Naeringsvaerdien  af  Roer  og  Byg  til  Fedning  og  om  Naeringsstofforholdets 

Betydning  for  Fodermidlernes  Naeringsvaerdi.  Beretning  111,  Fors0gslaboratoriet,  Copen¬ 

hagen,  1923. 

6  Andersen,  Biochem.  Zeitschr.,  1922,  130,  p.  143. 


150 


METABOLISM  OF  THE  FASTING  STEER 


geese  and  pigs,  however,  we  are  convinced  that  the  calorific  value  of  oxygen 
remains  remarkably  constant,  and  when  the  total  amount  of  oxygen  actually 
absorbed  by  animals  is  known,  and  particularly  when  the  respiratory 
quotient  is  at  or  near  1.00  (a  condition  always  prevailing  when  ruminants 
are  on  maintenance  rations),  if  the  total  oxygen  consumption  in  liters  is 
multiplied  by  the  calorific  value  of  oxygen  for  carbohydrates,  namely,  5.06, 
the  computed  heat-production  will  be  essentially  that  obtained  by  the 
Andersen  formula.  The  advantage  of  this  procedure  is  that  it  does  not 
introduce  into  the  heat  computation  the  inherent  errors  of  either  the  nitrogen 
determination  or  more  particularly  the  complicated  methane  determination. 
In  order  to  compare  the  heat  values  as  computed  by  these  two  different 
methods  we  have  summarized  Mpllgaard’s  experiments  in  Table  38.  In  the 
second  column  of  this  table  are  recorded  his  computations  of  the  heat-pro¬ 
duction  by  the  Andersen  formula,  the  protein  katabolized  and  the  methane 
produced  being  taken  into  consideration.*  In  the  third  column  are  recorded 
the  heat  values  obtained  by  multiplying  the  oxygen  determinations,  as 
found  with  Mpllgaard’s  respiration  apparatus,  by  the  calorific  value  of 
oxygen  per  liter,  5.06,  when  pure  carbohydrates  are  being  burned.  It  is 
seen  from  the  last  column  in  the  table  that  in  general  the  agreement  between 
the  two  methods  is  within  1  per  cent.  Thus  the  simpler  method  of  calcu¬ 
lation  lends  itself  to  those  experiments  where  nitrogen  determinations  are 
not  available  and  methane  can  be  determined  only  with  difficulty,  if  at  all. 
Indeed,  this  comparison  raises  the  question  as  to  whether  for  many  experi¬ 
ments  the  actual  determination  of  methane  is  of  any  significance  in  the 
computation  of  the  energy  output  of  the  ruminant. 

Conditions  Prerequisite  for  Comparable  Measurements  of 

Metabolism 

With  humans,  certain  conditions  have  been  stipulated  by  common  consent 
as  being  prerequisite  for  the  measurement  of  the  basal  metabolism,  if  the 
results  are  to  be  on  a  comparable  basis.  Those  factors  known  to  influence 
basal  metabolism  most  pronouncedly  are  thereby  either  entirely  eliminated 
or  in  large  part  minimized  by  the  prescribed  conditions.  Thus,  the  after¬ 
effect  of  food  is  minimized  by  insisting  that  the  measurements  be  made  at 
least  12  hours  after  the  last  meal,  which  should  not  be  too  large  in  amount 
or  contain  too  large  a  proportion  of  protein.  Some  writers  believe  that 
a  constant  ration  should  be  given  for  two  or  three  days  before  the  experi¬ 
ment,  but  this  procedure  is  generally  not  carried  out.  The  well-known 
influence  of  muscular  activity  is  eliminated  by  insisting  that  the  subject 
should  be  in  complete  muscular  repose,  and  the  after-effect  of  previous 
activity  is  ruled  out  by  requiring  that  the  subject  should  be  lying  down 
for  at  least  a  half  hour  before  the  measurements  are  made.  Psychic 
disturbance  must  also  be  avoided,  and  the  subject  should  be  in  a  comfort¬ 
able  environmental  temperature  and  with  a  normal  body  temperature. 

In  studying  ruminants  it  is  highly  desirable  to  have  some  such  equally 
satisfactory  basis  for  securing  comparable  metabolism  measurements.  But 
practically  all  the  conditions  prescribed  for  the  basal  metabolism  measure- 


GASEOUS  METABOLISM  AND  ENERGY  RELATIONSHIPS 


151 


ments  of  humans  are  impracticable  with  ruminants.  The  prolonged  reten¬ 
tion  of  food  materials  in  the  paunch  of  the  ruminant  makes  the  question 
of  withholding  of  food  a  difficult  one,  and  the  point  at  which  the  true 
fasting-level  is  reached  is  not  sharply  defined.  Some  of  our  experiments 
throw  light  upon  this  subject  (see  p.  204).  Enforced  quiet  is  impracticable, 
since  animals  can  not  cooperate  as  can  intelligent  human  beings.  It  is 
usually  feasible  to  have  the  human  subject  rest  quietly  in  bed,  well  covered, 
but  animals  will  not  lie  down  at  command,  nor  will  they  remain  motionless. 
In  our  earlier  research  on  undemutrition  in  steers  it  became  necessary  to 
require  certain  easily  insured  conditions  for  the  measurement  of  the  “stand¬ 
ard  metabolism.”  It  is  a  matter  of  regret  that  we  chose  this  terminology, 
for  Krogh,a  with  his  critical  insight,  has  objected  to  the  term  “basal  metab¬ 
olism”  as  determined  with  humans  and  wishes  to  propose  the  expression 
“standard  metabolism.”  Our  use  of  the  expression  was  simply  to  designate 
that  the  metabolism  was  measured  on  a  standardized  basis  for  purposes 
of  comparison.  Admittedly,  the  metabolism,  as  so  measured,  could  not 
have  been  the  basal  or  lowest  metabolism.  The  conditions  prescribed  for 
the  measurement  of  the  “standard  metabolism”  were  that  the  animals 
should  have  been  24  hours  without  food,  i.  e.,  twice  as  long  as  in  the  case 
of  humans,  and  that  they  should  be  standing. 

A  greater  energy  expenditure  is  seemingly  required  to  support  the  animal 
body  in  the  standing  position  than  in  the  lying  position.  This  difference 
due  to  the  position  of  the  body  has  long  been  a  matter  of  experimental 
study,  with  widely  differing  results.  Certain  experiments  which  contributed 
information  in  a  minor  way  on  this  subject  were  reported  in  our  earlier 
monograph.6  Under  the  special  conditions  of  these  tests  it  was  found  that 
the  increment  in  metabolism  due  to  standing  was  about  17  per  cent.  This 
difference  between  the  metabolism  in  the  standing  and  in  the  lying  positions 
has  of  course  no  application  to  experiments  made  under  standard  condi¬ 
tions  (which  stipulate  that  the  animal  should  be  standing  only),  but  it  is 
of  great  significance  in  a  long  experiment  of  24  hours,  for  example,  when 
the  animal  at  will  alternates  between  standing  and  lying.  In  the  latter 
case  the  attempt  is  made  to  compute  the  total  metabolism  for  24  hours 
on  some  basis  of  definite  proportion  between  the  time  spent  lying  and 
standing.  For  all  workers  who  employ  the  24-hour  period,  some  method 
of  calculating  the  total  24-hour  metabolism  on  a  comparable  basis  is  essen¬ 
tial,  since  the  animal  will  not  either  lie  down  or  stand  up  for  24  hours. 
This  matter  will  be  discussed  more  at  length  in  a  later  chapter  (see  pp 
211  to  213). 

The  most  recent  contribution  on  this  point  is  the  article  published  by 
Fries  and  Kriss,c  who  report  some  work  carried  out  in  Professor  Armsby’s 
laboratory.  Although  their  final  calculations  are  based  exclusively  on  the 
data  secured  upon  one  cow,  No.  874,  weighing  400  kg.,  the  experimental 
conditions  were,  they  state,  seemingly  ideal.  On  the  assumption  that 
animals  of  varying  weights  would  have  a  greater  energy  consumption  when 

°  Krogh,  The  respiratory  exchange  of  animals  and  man,  London  and  New  York,  1916,  pp.  56 
et  seq. 

6  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  pp.  215  et  seq. 
e  Fries  and  Kriss,  Am.  Journ.  Physiol.,  1924,  71,  p.  60. 


152 


METABOLISM  OF  THE  FASTING  STEER 


standing  than  when  lying  in  proportion  to  the  two-thirds  power  of  their 
body-weight,  these  authors  propose  a  series  of  factors  for  correcting  the 
total  heat-production,  as  measured,  to  a  standard  day  of  12  hours  standing 
and  12  hours  lying,  for  animals  ranging  in  weight  from  275  to  575  kg. 
Thus,  they  express  the  belief  that  with  an  animal  of  275  kg.  the  “net 
energy  per  hour”  is  20.5  calories  greater  when  the  animal  is  standing  than 
when  lying;  with  an  animal  of  400  kg.  it  is  26.3  calories  greater,  and  with 
an  animal  of  575  kg.  it  is  33.5  calories  greater.  These  factors  are  now 
regularly  employed  for  application  to  all  of  the  experimental  work  at  the 
Pennsylvania  Institute  of  Animal  Nutrition.® 

In  view  of  the  desirability  of  securing  comparable  metabolism  measure¬ 
ments,  all  of  the  “standard  metabolism”  measurements  reported  in  this 
present  monograph  were  made  24  hours  after  food  and  with  the  steer  in 
the  standing  position.  During  those  fasting  experiments  and  those  experi¬ 
ments  made  immediately  after  the  ingestion  of  feed,  which  involved  short 
half-hour  periods  of  measurement,  the  animals  were  likewise  studied  in 
most  instances  in  the  standing  position,  but  the  time  intervals  following 
food  ingestion  were  of  course  greater  or  less  than  24  hours.  In  the  3-day 
and  4-day  experiments  involving  8-hour  periods  of  measurement,  the  steer 
was  allowed  to  lie  or  stand  at  will.  Since  the  4-day  experiments  were  made 
expressly  to  study  the  influence  of  the  character  and  amount  of  food,  the 
influence  of  fasting,  and  the  influence  of  environmental  temperature  upon 
metabolism,  it  would  seem  as  if  a  better  comparison  of  the  values  obtained 
might  be  secured  if  the  metabolism  data  were  computed  to  a  standard 
basis  on  the  supposition  that  the  animal  would  be  standing  12  hours  and 
lying  12  hours.  The  Pennsylvania  investigators  used  this  basis  for  their 
work  because  they  found  that  usually  their  animals  stood  not  far  from  12 
hours  or  half  of  the  day.  During  the  fasting  experiments,  however,  our 
steers  showed  a  disposition  to  lie  down  for  a  greater  proportion  of  the  time, 
and  it  is  probable  that  a  better  basis  for  the  comparison  of  the  fasting  data 
would  be  to  compute  the  metabolism  for  perhaps  15  hours  lying  and  9 
hours  standing.  Since  the  best  method  of  handling  such  data  is  still  prob¬ 
lematical,  however,  the  fasting  metabolism  of  our  steers  has  not  been 
corrected  to  any  uniform  basis  of  lying  and  standing.  (For  further  discus¬ 
sion  of  this  point  see  p.  202.) 

The  Physiological  Comparison  of  Animals 
Comparison  on  the  Basis  of  Live  Body-weight 

In  comparing  the  metabolism  of  one  animal  with  that  of  another,  one 
of  the  simplest  attempts  to  equalize  differences  in  size  has  been  to  refer 
the  metabolism  to  a  uniform  basis  of  body-weight.  A  large  adult  steer 
commonly  weighs  around  500  kg.,  and  it  has  therefore  been  the  custom  to 
compute  the  heat-production  of  these  large  ruminants  per  500  kg.  of  body- 
weight.  Some  writers  have  referred  the  heat-production  to  the  two-thirds 
power  of  the  body- weight.  If  physiologists  are  to  accept  the  two-thirds 
power  of  the  body-weight  as  an  expression  of  the  law  of  growth  and  the 
probable  increase  in  active  protoplasmic  tissue,  without  reference  to  surface 


“  Forbes,  Science,  1926,  63,  p.  311. 


PHYSIOLOGICAL  COMPARISON  OF  ANIMALS 


153 


area,  we  are  heartily  in  sympathy  with  this  method  of  comparing  the 
metabolism  of  animals  of  the  same  species  but  of  different  sizes.  In  all 
of  our  comparisons  of  the  metabolism  of  our  four  fasting  steers  on  the  basis 
of  live  body-weight,  however,  we  have  computed  the  heat-production  per 
500  kg.  of  body-weight,  which  is  practically  the  equivalent  of  the  heat- 
production  per  kilogram  of  body-weight  so  commonly  reported  for  man 
and  small  animals.  We  have  not  referred  the  metabolism  to  the  two-thirds 
power  of  the  body-weight,  since  this  computation  brings  in  the  surface-area 
factor  and  we  have  felt  that  it  is  better  to  compute  the  surface  area  in  a 
different  way. 

Comparison  on  the  Basis  of  Body-surface 

The  persistent  popularity  of  the  conception  that  the  surface  area  is  an 
important  factor  controlling  metabolism  and  the  persistent  efforts  of  physi¬ 
ologists  to  compare  the  metabolism  of  individuals  of  different  ages  and 
sizes  and  under  different  conditions  of  nutrition  on  the  basis  of  the  heat- 
production  per  unit  of  surface  area  make  it  necessary  to  compare  the 
metabolism  of  animals  on  this  same  basis,  irrespective  of  any  personal 
credence  in  the  significance  of  this  comparison.  For  many  years  the 
general  conception  has  prevailed  that  the  metabolism  of  warm-blooded 
animals  is  proportional  to  the  surface  area  of  the  animal  and  that  the 
basal  heat-production  per  square  meter  of  body-surface  per  24  hours  is 
essentially  the  same  (i.  e.,  not  far  from  1,000  calories)  with  all  warm¬ 
blooded  animals,  regardless  of  species,  size,  or  age.  It  was  recognized  by 
Rubner,  however,  that  the  heat-production  of  different  individuals  per 
square  meter  of  body-surface  is  the  same  only  under  the  same  general 
conditions  of  nutrition.  Yet  the  extensive  use  of  the  surface  area  as  a 
basis  for  the  comparison  of  metabolism  in  pathological  cases  necessarily 
includes  a  large  proportion  of  humans  in  a  poor  state  of  nutrition.  Since 
such  comparisons  have  been  made  without  the  slightest  reservations  on 
the  part  of  medical  men,  it  therefore  seems  proper  to  compute  the  heat- 
production  per  square  meter  of  body-surface  of  our  steers,  although  we 
fully  recognize  that  they  were  not  in  the  same  nutritive  condition  at  all 
times  and  hence  should  not,  strictly  speaking,  be  compared  on  this  basis. 
Indeed,  the  Nutrition  Laboratory  is  distinctly  out  of  sympathy  with  the 
general  belief  that  the  metabolism  of  all  warm-blooded  animals  is  the 
same  per  unit  of  surface  area.  The  method  of  comparison  is,  however, 
justified  on  the  basis  of  usage,  provided  a  false  significance  is  not  attached 
to  it  and  that  a  causal  relationship  between  body-surface  and  heat-produc¬ 
tion  is  not  insisted  upon. 

METHOD  OF  ESTIMATING  THE  SURFACE  AREA  OF  FASTING  STEERS 

It  is  unnecessary  at  this  point  to  discuss  the  basis  and  derivation  of  the 
so-called  “surface-area  law,”  for  this  subject  has  been  considered  exten¬ 
sively  in  an  earlier  publication  of  the  Nutrition  Laboratory.®  If  com¬ 
parisons  of  the  metabolism  are  to  be  made,  however,  with  reference  to  the 
surface  area,  the  measurement  of  this  factor  must  be  accurate.  In  the 


°  Harris  and  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  279,  1919,  pp.  129  et  seq. 


154 


METABOLISM  OF  THE  FASTING  STEER 


literature,  new  formulas  for  estimating  body-surface,  employing  constants  of 
various  sizes,  are  continually  appearing.  The  experimental  bases  for  these 
constants  will  not,  we  believe,  withstand  the  closest  criticism.  Thus, 
Du  Bois®  has  shown  clearly  the  great  error  possible  in  the  constant  in 
Meeh’s* 6  formula,  so  generally  used  for  computing  the  body-surface  of 
humans.  Actual  measurements  of  the  surface  area  of  other  animals  are 
scarce,  and  the  computation  of  the  surface  area  of  animals  of  various 
sizes  still  remains  debatable.  Du  Bois®  has  placed  the  body-surface  meas¬ 
urements  of  humans  upon  an  accurate  footing,  and  for  this  reason  probably 
more  is  known  about  the  surface  area  of  humans  than  of  any  other  living 
organism  at  the  present  time,  but  knowledge  with  regard  to  the  surface 
area  of  ruminants  is  by  no  means  so  definite  or  complete. 

In  the  attempt  to  approximate  as  closely  as  possible  the  probable  surface 
area  of  our  first  groups  of  steers  which  were  subjected  to  undemutrition, 
the  earlier  literature  regarding  body-surface  measurements,  and  particu¬ 
larly  the  more  recent  extensive  measurements  of  Moulton, d  were  considered. 
In  Moulton’s  formula  the  warm,  empty  weight  of  the  animal  after  slaughter 
enters  into  the  calculation.  It  was  impossible  in  our  work  with  steers  to 
determine  the  warm,  empty  weight  and  it  therefore  had  to  be  computed. 
In  the  estimation  of  the  surface  areas  of  our  animals  studied  in  the  research 
on  undemutrition  their  relative  nutritive  states,  as  appraised  by  an  expert 
judge  of  livestock,  were  used  as  bases  for  assumptions  of  the  probable 
warm,  empty  weights  and  Moulton’s  formula  (S  =  W%  X  0.1186)  involving 
the  use  of  the  warm,  empty  weight  was  employed.  This  method  of  compu¬ 
tation  was  given  extensive  treatment  in  our  earlier  monographs  Since  this 
monograph  was  published,  an  article  by  Hogan  and  Skoubyf  (who  suc¬ 
ceeded  Moulton)  has  appeared,  in  which  changes  are  suggested  in  Moulton’s 
body-surface  formula,  the  chief  of  which  is  the  elimination  of  the  difficult 
determination  of  the  warm,  empty  weight  by  the  use  of  a  different  constant. 
Thus,  the  five-eighths  power  of  the  live  weight  of  the  animal  is  multiplied 
by  the  constant  0.1081  instead  of  0.1186,  and  Hogan  finds  that  the  surface 
areas  as  thus  computed  are  confirmed  by  areas  computed  by  a  second 
formula  in  which  the  length  of  the  animal  is  taken  into  consideration. 

Although  the  use  of  the  warm,  empty  weight  undoubtedly  is  of  value 
in  many  connections  and  is  proposed  urgently  by  Moulton  for  live  animals, 
the  uncertainty  regarding  the  amount  of  the  fill  makes  it  difficult  to  approx¬ 
imate  such  a  weight.  Particularly  is  this  true  during  the  pronounced 
transitory  stage  of  the  contents  of  the  intestinal  tract  incidental  to  pro¬ 
longed  fasting.  The  actual  number  of  cases  where  an  animal  has  been 
slaughtered  after  fasting  and  the  fill  determined  are  so  few  that  almost 
nothing  is  known  with  regard  to  the  amount  of  fill  in  cattle  under  such 
conditions.  The  early  observations  of  Grouven  indicate  that  the  mass  of 

°  Du  Bois  and  Du  Bois,  Arch.  Intern.  Med.,  1915,  15,  p.  868. 

6  Meeh,  Zeitschr.  f.  Biol.,  1879,  15,  p.  425. 

c  Du  Bois  and  Du  Bois,  Arch.  Intern.  Med.,  1916,  17,  p.  863. 

d  Moulton,  Journ.  Biol.  Chem.,  1916,  24,  pp.  303  et  seq.;  Armsby,  Fries,  and  Braman,  Journ. 
Agric.  Res.,  1918,  13,  p.  47;  Trowbridge,  Moulton,  and  Haigh,  Univ.  Missouri,  Agric.  Expt.  Sta. 
Bull.  18,  1915,  pp.  11  and  41. 

e  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  pp.  220  et  seq. 

1  Hogan  and  Skouby,  Journ.  Agric.  Research,  1923,  25,  p.  419. 


PHYSIOLOGICAL  COMPARISON  OF  ANIMALS 


155 


fill  was  not  materially  decreased  in  his  fasting  oxen,  although  the  amount 
of  dry  matter  decreased  enormously. 

In  attempting  to  approximate  the  surface  areas  of  our  fasting  steers,  we 
at  first  employed  the  same  formula  as  with  the  steers  on  undemutrition, 
i.  e.,  Moulton's  formula  involving  the  use  of  the  warm,  empty  weight. 
Estimates  of  the  various  nutritive  states  and  the  probable  fill  had  to  be 
made  in  order  to  use  this  formula,  and  aberrant  results  were  invariably 
found  which  could  not  be  explained.  In  a  few  cases  the  lengths  of  our 
animals  were  known,  although  these  lengths  were  not  exactly  the  same  as 
that  used  by  Hogan  in  his  body-surface  formula.  Nevertheless,  it  was 
believed  that  these  lengths,  although  subject  to  a  slight  correction,  could 
properly  be  used,  and  accordingly  for  one  of  our  animals  the  body-surface 
was  calculated  during  and  preceding  a  fasting  period,  upon  the  basis  of 
Hogan's  formula,  i.  e.,  S—  IP-4  X  L0-6  X  217.02.  In  this  formula  W  repre¬ 
sents  the  live  weight  of  the  animal  in  kilograms,  L  the  length  of  the  body 
in  centimeters  from  the  point  of  withers  to  the  end  of  the  ischium,  and 
217.02  is  the  constant  for  cattle.  With  this  formula,  Hogan  maintains  that 
the  body-surface  can  be  computed  with  a  maximum  error  of  less  than 


Sq.m. 


Fig.  8. — Body-surface  in  square  meters  referred  to  live  weight 

in  kilograms. 

The  body-surface  is  computed  from  the  formula  S  =  W'0,i  X 
0.1081,  in  which  W  represents  the  live  weight. 

±  5.5  per  cent.  A  comparison  of  the  body-surface  of  one  of  our  fasting 
steers  as  computed  from  Moulton’s  formula  involving  empty  weight,  from 
Hogan's  length  formula,  and  from  Hogan’s  modification  of  the  Moulton 
formula  (S  =  W%  X  0.1081) ,  indicates  that  fairly  closely  agreeing  results 
can  be  obtained  by  the  two  latter  methods  and  that  less  aberrant  values 
are  thus  obtained  for  the  body-surface  of  steers  during  periods  of  fasting 
and  realimentation.  Hence,  since  the  lengths  of  our  fasting  animals  were 
determined  only  once  throughout  the  entire  experimental  series,  we  have 
felt  justified  in  using  in  all  of  the  body-surface  computations  reported  in 
this  monograph  the  formula  S  =  W%  X  0.1081,  in  which  W  is  the  live 


156 


METABOLISM  OF  THE  FASTING  STEER 


weight.  Indeed,  so  satisfactory  have  we  found  this  formula  and  so  con¬ 
vinced  are  we  that  this  is  the  best  available  approximation  of  the  true 
surface  area,  that  we  have  plotted  a  curve  giving  the  surface  areas  of 
animals  with  live  weights  ranging  from  200  to  750  kg.  (See  Fig.  8.)  This 
curve,  as  the  nature  of  the  formula  will  show,  is  not  a  straight  line,  but 
from  it  the  surface  area  can  be  read  directly,  if  the  live  weight  of  the 
animal  is  known.  In  considering  the  heat-production  per  square  meter 
of  body-surface  in  this  monograph,  all  of  the  areas  employed  in  our 
calculations  were  taken  from  this  curve. 

In  thus  emphasizing  the  desirability  of  securing  the  greatest  accuracy 
in  computations  of  the  surface  area  of  these  animals,  we  wish  to  affirm 
that  whatever  the  value  of  the  actually  known  surface  area  of  these  animals 
may  be,  we  can  not  subscribe  to  the  prevailing  notion  that  the  surface  area 
is  indissolubly  associated  with  the  heat-production,  and  in  this  report  the 
heat-production  has  been  calculated  per  unit  of  surface  area  solely  as  a 
concession  to  the  large  number  of  physiologists  who  are  still  wont  to  think 
of  the  heat-production  from  this  singular  point  of  view. 

Method  of  Presenting  the  Gaseous  Metabolism  Data 

The  large  mass  of  data  accumulated  in  this  research  may  best  be  con¬ 
sidered,  not  in  the  chronological  order  of  the  experiments,  but  by  grouping 
the  data  according  to  the  various  problems  studied.  Separate  treatment 
will  therefore  be  given  to  the  metabolism  measurements  under  three  main 
heads,  i.  e.,  the  fasting  experiments,  the  standard  metabolism  experiments, 
and  the  experiments  in  which  the  effect  of  the  ingestion  of  food  was  studied. 

The  fasting  experiments  themselves  will  be  discussed  in  three  general 
groups.  The  fasts  of  5  to  14  days  and  the  short  2-day  and  3-day  fasts 
represent  one  group  made  with  the  same  general  technique,  although  at 
different  nutritive  levels.  Thus,  in  these  experiments  the  metabolism  was 
usually  measured  during  4  half-hour  periods  with  the  animal  in  the  standing 
position.  This  type  of  experiment  comprises  the  bulk  of  the  metabolism 
measurements.  In  these  experiments  the  metabolism  was  measured  only 
for  a  period  of  about  l1/^  or  2  hours,  and  although  the  results  have  been 
computed  to  the  24-hour  basis,  the  values  must  of  necessity  be  somewhat 
higher  than  they  would  have  been  had  the  metabolism  been  measured 
during  the  total  24  hours,  for  the  conditions  of  the  experiment  required 
that  the  animal  should  always  be  standing.  A  second  group  of  fasting 
experiments  was  therefore  made,  to  secure  a  complete  picture  of  the  24-hour 
metabolism.  In  these  experiments  the  metabolism  was  measured  in  con¬ 
secutive  8-hour  periods  during  3  continuous  days,  beginning  24  hours  after 
withdrawal  of  food,  and  the  animal  was  allowed  to  lie  or  stand  at  will. 
Finally,  to  throw  light  upon  the  transitional  period  between  feeding  and 
fasting,  with  particular  reference  to  the  character  and  amount  of  the 
previous  feed-level,  and  also  to  throw  light  upon  the  influence  of  environ¬ 
mental  temperature,  a  third  group  of  experiments  was  made.  In  this  series 
the  metabolism  was  measured  in  consecutive  8-hour  periods  and  each 
experiment  lasted  for  4  days,  comprising  2  days  on  feed  followed  by  2  days 
of  fasting. 


Table  39. — Respiratory  quotients  of  steers  during  fasts  of  5  to  days 


METABOLISM  DURING  FASTING 


157 


1  Assumed,  since  quotients  actually  determined  seemed  aberrant.  2  Based  on  quotients  slightly  below  0.70. 

*  No  determinations  of  the  respiratory  quotient  were  made  on  the  eleventh  day. 


158 


METABOLISM  OF  THE  FASTING  STEER 


In  presenting  these  data  it  is  deemed  best  to  record  in  the  various  tables 
not  only  the  actual  measurements  of  the  carbon-dioxide  production  and 
the  respiratory  quotient,  but  the  derived  computations  of  the  heat-produc¬ 
tion  and  other  related  measurements  obtained  during  the  same  24  hours  as 
the  gaseous  metabolism  measurement,  i.  e.,  the  records  of  the  heart-rate, 
the  insensible  loss,  and  the  environmental  temperature. 

Metabolism  During  Fasting 
Respiratory  Quotient 

The  determination  of  the  respiratory  quotient  is  of  value  in  two  respects. 
In  the  first  place,  the  respiratory  quotient  indicates  the  character  of  the 
metabolic  processes  during  the  period  of  experiment.  When  the  steer  is 
receiving  full  feed,  the  respiratory  quotient  will  be  above  1.00,  indicating 
carbohydrate  combustion.  When  feed  is  withdrawn,  the  quotient  will  fall 
as  the  fast  progresses  and  ultimately  will  reach  a  value  not  far  from  0.70, 
characteristic  of  fat  combustion.  Inasmuch  as  practically  all  of  our  experi¬ 
ments  dealt  with  the  early  and  late  stages  of  fasting,  the  determinations 
of  the  respiratory  quotient  therefore  serve  to  indicate  the  rapidity  at  which 
the  metabolism  reaches  the  fasting-level.  The  second,  and  perhaps  the 
most  important,  use  of  the  respiratory  quotient  is  that  it  indicates  the 
calorific  value  of  carbon  dioxide  to  be  used  in  the  calculation  of  the  heat- 
production.  Since  the  carbon-dioxide  production  of  the  steers  was  actually 
determined,  as  well  as  the  relationship  between  the  carbon-dioxide  produc¬ 
tion  and  the  oxygen  consumption,  i.  e.,  the  respiratory  quotient,  it  is  possible 
to  compute,  on  the  one  hand,  the  oxygen  consumption,  and,  on  the  other 
hand,  to  secure  a  more  accurate  factor  for  the  calorific  value  of  carbon 
dioxide  in  the  computation  of  the  probable  heat  produced. 

The  respiratory  quotient  plays  its  greatest  role  in  our  researches  as  an 
index  of  the  probable  calorific  value  of  carbon  dioxide.  Consequently, 
before  the  discussion  of  the  quantitative  amount  of  carbon  dioxide  pro¬ 
duced,  and  particularly  of  the  heat  relationships,  a  consideration  of  the 
actually  determined  respiratory  quotients  is  desirable.  The  determina¬ 
tions  made  during  the  series  of  fasts  of  5  to  14  days  will  first  be  examined, 
and  the  data  are  accordingly  given  in  Table  39.  The  results  have  been 
computed  only  to  two  significant  figures. 

The  first  fast  for  which  respiratory  quotients  could  be  determined  was 
the  longest  one  of  14  days,  because  the  Carpenter  gas-analysis  apparatus 
was  not  installed  in  time  to  make  analyses  for  the  first  two  fasts.  It  is 
perhaps  not  surprising,  therefore,  that  seemingly  aberrant  quotients  were 
occasionally  found.  It  has  been  assumed  that  quotients  less  than  0.70  in 
all  probability  represent  technical  errors.  Accordingly,  in  those  instances 
where  the  gas  analyses  gave  quotients  slightly  below  0.70,  a  quotient  of 
0.70  has  been  assumed,  since  this  value  is  not  far  from  the  quotient  actually 
found.  Irrespective  of  this  fact,  the  general  picture  of  the  trend  of  the 
respiratory  quotient  as  the  fast  progresses  is  clear.  Prior  to  the  different 
fasts  the  quotient  was  about  1.00  or  above,  depending  somewhat  upon  the 
character  of  the  food  and  probably  the  time  since  the  last  food  was  taken. 
On  the  first  day  of  fasting,  i.  e.,  22  to  32  hours  after  food,  when  there  was 


METABOLISM  DURING  FASTING 


159 


still  considerable  material  in  the  intestinal  tract,  the  quotient  is  consider¬ 
ably  below  1.00  in  most  instances,  ranging  from  0.73  to  0.97,  and  being  on 
the  average  0.83.  On  the  second  day  of  fasting  there  is  a  further  drop 
with  all  four  steers.  On  the  third  day  the  quotients  of  steer  D  are  slightly 
lower.  The  values  for  steer  C  tend  to  be  a  little  higher  than  those  for 
steer  D  on  the  third  day,  although  one  must  speak  of  a  variability  of  0.02 
in  the  respiratory  quotient  with  considerable  reserve.  After  the  third  day 
the  quotients  are  essentially  constant.  The  small  amounts  of  food  given 
to  the  steers  following  the  fasts  almost  invariably  resulted  in  an  increase 
in  the  quotient,  this  increase  depending  upon  the  time  when  digestion  began 
and  the  amount  of  carbohydrate  actually  burned. 

In  the  fasts  of  December  1921  and  January  1922,  with  steers  C  and  D, 
the  respiratory  quotient  was  not  determined,  and  it  was  necessary  in  the 
computation  of  the  heat  values  for  these  fasts  to  assume  quotients,  which, 
as  a  matter  of  fact,  are  based  upon  average  values  derived  from  Table  39. 
Additional  information  regarding  the  respiratory  quotients  during  the  first 
few  days  of  fasting  was  secured  in  the  series  of  short  2-day  and  3-day  fasts, 
and  this  evidence  was  also  used  in  making  the  assumptions  of  the  most 
probable  quotients  to  be  used  for  the  first  two  long  fasts.  These  data  are 
given  in  Table  40,  from  which  it  is  seen  that  25  to  26  hours  after  food 
ingestion  the  respiratory  quotient  is  0.83  on  the  average,  and  that  47  to 
50  hours  after  food  it  is  0.76.  In  January  1923,  a  3-day  fast  was  carried 
out  with  each  animal,  and  a  quotient  of  0.72  was  noted  with  steer  C  and 
0.70  with  steer  D,  72  hours  after  food. 


Table  40. — Respiratory  quotients  of  steers  2J+  and  48  hours  after  food  ( maintenance  level  of 

nutrition) 


Steer  and  dates 
of  fasts 
(1923) 

Hours  without  food 

Steer  and  dates 
of  fasts 

Hours  without  food 

25  to  26 

47  to  50 

(1923) 

25  to  26 

47  to  50 

Steer  C: 

Jan.  4  and  5. . . . 

0.83 

>0.73 

Steer  D: 

Jan.  10  and  11.. .  . 

0.83 

>0.73 

Jan.  22  and  23 ...  . 

.83 

.76 

Jan.  18  and  19 . . . 

.81 

.74 

Jan.  29  and  30. _ 

.82 

.73 

Jan.  26  and  27. . . . 

.82 

.78 

Feb.  6  and  7 ... . 

.83 

.73 

Feb.  2  and  3.... 

.86 

.75 

Feb.  12  and  13 ... . 

.84 

.74 

Feb.  9  and  10. .  .  . 

.78 

.77 

Feb.  19  and  20.  .  .  . 

.82 

.70 

Feb.  15  and  16. . .  . 

.82 

.75 

Mar.  2  and  3 .  .  .  . 

.83 

.79 

Feb.  23  and  24..  . . 

.83 

.73 

Mar.  9  and  10.  .  .  . 

.84 

.77 

Mar.  6  and  7. . . . 

.83 

s  (.75) 

Mar.  16  and  17. . .  . 

.80 

.77 

Mar.  14  and  15. .  .  . 

.84 

.79 

Mar.  23  and  24 ... . 

.86 

.79 

Mar.  21  and  22..  .  . 

.86 

.76 

Average . 

.83 

.75 

Average .... 

.83 

.76 

1  Determinations  made  72  hours  after  food  in  the  January  experiments  showed  a  quotient  of 
0.72  for  steer  C  and  0.70  for  steer  D. 

1  Assumed ;  not  included  in  average. 


In  view  of  the  picture  shown  by  the  respiratory  quotients  in  Tables  39 
and  40,  and  in  consideration  of  the  fact  that  the  true  fasting  state  is  repre¬ 
sented  by  a  katabolism  essentially  of  fat,  it  can  be  seen  that  the  steer  is 
burning  essentially  fat  on  the  third  day  of  fasting.  The  effect  of  the  previous 


160 


METABOLISM  OF  THE  FASTING  STEER 


state  of  nutrition  is  not  so  pronounced  as  was  at  first  thought  would  be 
the  case.  Thus,  as  seen  from  Table  39,  the  respiratory  quotient  noted  with 
steer  C  in  the  fast  in  March  1924,  following  submaintenance  feeding,  was 
0.82  on  the  first  day  and  0.74  on  the  second  day.  An  even  lower  quotient 
of  0.74  on  the  first  day  was  found  in  the  fast  following  pasture  in  November 
1922.  On  the  other  hand,  the  lowest  respiratory  quotient  on  the  first  day  of 
fasting,  namely,  0.73,  was  noted  with  steer  D  in  the  fast  following  sub¬ 
maintenance  feeding  in  March  1924.  The  general  picture,  however,  is  that 
a  fat  combustion  occurs  not  far  from  the  third  day  of  fasting. 

Further  data  regarding  the  influence  of  different  feed-levels  upon  the 
respiratory  quotient  during  the  first  day  of  fasting  were  secured  in  the 
series  of  “standard  metabolism”  experiments,  in  which  the  animals  were 
studied  24  hours  after  their  last  feed,  both  at  a  maintenance  and  a  sub¬ 
maintenance  level  of  nutrition.  In  28  experiments  during  maintenance 
feeding  the  average  respiratory  quotient  of  steer  C  was  found  to  be  0.84, 
and  in  27  experiments  with  steer  D  it  was  found  to  be  0.83.  Following 
submaintenance  feeding,  steer  C  had  an  average  respiratory  quotient  for 
12  experiments  of  0.80,  and  steer  D  had  an  average  quotient  for  14  experi¬ 
ments  of  0.77.  (See  Tables  55  and  56,  pp.  226  and  227,  for  details.) 


Table  41. — Respiratory  quotients  as  affected  by  ingestion -  of  food ,  steers  C  and  D 


Steer  and  date 

Last  feed 
before 
experiment 

Hours 

without 

food 

Respir¬ 

atory 

quotient 

(average) 

Daily  feed-level  for  at 
least  2  weeks  prior 
to  experiment 

Hay 

Meal 

Steer  C: 

kg. 

kg. 

May  31,  1922 . 

3.2 

2.0 

0  to  4 

1.12 

9  kg.  hay;  4  kg.  meal. 

June  1,  1922 . 

4.5 

2.0 

4  6 

0.96 

Do. 

Nov.  6,  1922 . 

Grass 

2  4 

1.00 

Pasture. 

Mar.  28,  1923 . 

3.6 

1.0 

2  4 

1.06 

9  kg.  hay;  2  kg.  meal.1 

Apr.  9,  1923 . 

3.8 

2  4 

0.96 

Do. 

Apr.  16,  1923 . 

4.5 

2  3 

1.07 

Do. 

Nov.  5,  1923 . 

Gr 

ass 

18  20 

0.93 

Pasture. 

Steer  D: 

Apr.  5,  1922 . 

4.5 

1.5 

8  10 

1.10 

9  kg.  hay;  3  kg.  meal. 

Apr.  17,  1922 . 

4.5 

1.5 

8  9 

0.99 

Do. 

May  31,  1922 . 

3.9 

2.0 

7  9 

0.88 

9  kg.  hay;  4  kg.  meal. 

June  1,  1922 . 

2.7 

2.0 

%  3 

1.17 

Do. 

Nov.  6,  1922 . 

Grass 

7  8 

0.86 

Pasture. 

Mar.  27,  1923 . 

3.6 

1.0 

3  4 

1.08 

9  kg.  hay;  2  kg.  meal.1 

Apr.  10,  1923 . 

4.5 

2  3 

1.16 

Do. 

Apr.  17,  1923 . 

4.5 

2  4 

1.03 

Do. 

1  Intermittent  2-day  fasts  between  Jan.  4  and  Mar.  24. 


In  this  consideration  of  respiratory  quotients  no  special  attention  has 
been  paid  to  the  presence  of  methane  and  no  attempt  has  been  made  to 
differentiate  between  the  carbon  dioxide  of  fermentation  and  cleavage  and 
the  carbon  dioxide  of  true  metabolism.  The  respiratory  quotients  reported 
represent  the  actual  determinations  with  the  Carpenter  gas-analysis  appa¬ 
ratus.  In  general,  the  data  show  that  the  ruminant  is  somewhat  sluggish 


METABOLISM  DURING  FASTING 


161 


in  adjusting  himself  to  a  fat  combustion  during  fasting  (which  is  to  be 
expected,  owing  to  the  large  amount  of  feed  residues  in  the  intestinal  tract) , 
but  almost  immediately  responds  to  the  ingestion  of  carbohydrate  following 
a  fast  of  several  days. 

The  influence  of  the  ingestion  of  food  upon  the  respiratory  quotient  under 
normal  conditions  of  feeding  and  normal  body  reserves  is  well  brought 
out  in  Table  41.  Several  short  experiments,  comprising  usually  4  half-hour 
periods,  were  made  during  the  first  few  hours  after  food  ingestion.  The 
feed  varied  from  pasturage  to  a  maximum  of  4.5  kg.  of  timothy  hay  and 
2  kg.  of  meal.  In  these  experiments  the  respiratory  quotient  as  a  rule  was 
found  to  be  about  1.00  or,  in  some  cases,  a  little  higher.  The  average 
respiratory  quotient  of  both  animals  in  the  15  experiments  reported  in 
Table  41  is  1.02. 

Carbon-dioxide  Production 

Carbon  dioxide,  as  the  main  gaseous  product  studied  in  connection  with 
these  researches  (the  respiration  chamber  being  designed  in  the  first  place 
for  the  determination  of  this  compound) ,  assumes  the  greatest  significance 
in  the  study  of  the  metabolism  of  these  steers.  It  was  recognized  at  the 
start  that  the  various  sources  of  carbon  dioxide  are  complex  with  the 
ruminant.  There  is,  first,  the  carbon  dioxide  resulting  from  the  true  oxida¬ 
tion  of  body  material,  be  it  glycogen,  body  protein,  or  body  fat.  There 
is,  in  addition,  a  transformation  of  soluble  carbohydrate  to  fat,  with  the 
cleavage  of  carbon  dioxide,  the  so-called  “atypical”  carbon  dioxide,  and, 
finally,  there  is  an  appreciable  production  of  carbon  dioxide  as  a  result 
of  the  process  of  fermentation.  Because  of  the  reduction  in  digestive 
processes  and  in  energy  transformations  which  occur  during  fasting,  how¬ 
ever,  the  measurement  of  carbon  dioxide  alone  is  of  great  value.  In  our 
research  on  the  undernutrition  of  steers  it  was  found  that  when  the  animals 
were  on  a  maintenance  feed-level,  i.  e.,  not  burning  fat,  and  when  they 
were  on  a  submaintenance  feed-level,  i.  e.,  scantily  fed  and  drawing  upon 
body  material,  the  carbon-dioxide  production  was  extremely  suggestive 
of  the  energy  transformations.  With  the  elimination  of  feeding  and  the 
rapid  drafts  upon  body  stores  and  available  material  in  the  intestinal 
contents,  the  carbon-dioxide  production  becomes  an  even  clearer  index  of 
the  true  metabolic  process  than  is  the  case  during  any  condition  of  feeding. 
This  state  is  reached  rapidly  after  the  first  day  of  fasting,  when  the  metab¬ 
olism  may  be  complicated  by  the  combustion  of  material  amounts  of 
carbohydrate  substances. 

Accurate  measurements  of  the  carbon-dioxide  production  were  therefore 
obtained  throughout  the  entire  series  of  respiration  experiments.  Except 
during  the  last  year,  the  periods  of  measurement,  as  already  stated,  were 
usually  30  minutes  in  length,  and  the  values  reported  for  the  carbon- 
dioxide  production  are  based  in  general  upon  four  consecutive,  well-agreeing 
periods,  the  animal  being  with  few  exceptions  always  in  the  standing 
position.  During  the  last  year  of  the  experimental  series  the  periods  were 
8  hours  in  length.  The  discussion  in  this  chapter,  however,  will  be  confined 
to  the  average  values  based  on  the  half-hour  periods  with  the  animal, 
standing. 


162 


METABOLISM  OF  THE  FASTING  STEER 


Theoretically,  the  respiratory  quotient  should  not  be  affected  by  the 
size  or  weight  of  the  animal,  but  the  amount  of  carbon  dioxide  produced 
is  directly  proportional,  in  general,  to  the  size  of  the  animal.  In  the  presen¬ 
tation  of  the  data,  however,  it  seems  best  to  consider,  first,  the  actual 
measurements  of  carbon  dioxide  expressed  in  grams  per  half  hour,  on  the 
assumption  that,  although  in  any  particular  fast  the  animal  starts  at  a 
definite  weight  and  loses  weight  as  the  fast  goes  on,  the  changes  in  body- 
weight  are  not  great,  and  the  measurements  of  the  carbon-dioxide  produc¬ 
tion  are,  therefore,  more  or  less  comparable.  On  this  basis,  steers  C  and  D 
may  be  compared  with  each  other  and  steers  E  and  F  with  each  other, 
but  since  the  two  latter  steers  are  smaller  and  younger  animals,  they  may 
not  be  directly  compared  with  the  older  animals,  C  and  D,  without  further 
consideration  of  their  body-weights. 

The  carbon-dioxide  measurements  made  in  connection  with  the  fasts  of 
5  to  14  days  are  recorded  in  Table  42.  An  examination  of  the  data  for 
steers  C  and  D  shows  that  prior  to  the  fast  the  carbon-dioxide  production 
varies  from  120.5  to  172.2  grams  per  half  hour,  depending  largely  upon 
the  nature  and  amount  of  the  feed  received.  On  the  first  day  of  fasting, 
the  decrease  in  the  carbon-dioxide  excretion  is  enormous,  amounting  to 
almost  50  per  cent  in  two  of  the  cases  where  it  is  possible  to  make  the 
comparison  with  measurements  secured  prior  to  fasting.  Average  values 
for  steers  C  and  D  for  the  carbon-dioxide  production  on  the  first  day  of 
fasting  can  hardly  be  derived  from  the  data  in  this  table,  since  the  March 
fast  followed  submaintenance  feeding  and  the  two  November  fasts  followed 
pasture  feeding.  On  the  second  day  of  fasting  there  is  a  still  further 
decrease  in  the  carbon  dioxide  produced,  amounting  to  not  far  from  20 
grams  in  the  first  four  fasts  of  steers  C  and  D  which  followed  maintenance 
feeding,  and  amounting  to  12  and  8  gm.,  respectively,  with  steers  C  and  D 
in  the  fast  at  a  submaintenance  level.  On  the  third  day  there  is  in  general 
a  still  further  decrease,  save  in  the  March  fast  of  steer  C  following  sub¬ 
maintenance  rations.  On  the  fourth  day  the  decrease  is  somewhat  less, 
amounting  usually  to  but  3  or  4  gm.  On  the  fifth  day  nearly  a  constant 
value  is  reached,  and  for  several  days  thereafter  no  great  change  in  the 
elimination  takes  place.  In  the  14-day  fasts,  however,  there  is  a  still 
further  fall.  Thus,  in  the  case  of  steer  C,  a  minimum  value  of  43.6  gm. 
is  reached  on  the  fourteenth  day,  and  in  the  case  of  steer  D  a  minimum 
value  of  47.4  gm.  is  found  on  both  the  tenth  and  the  fourteenth  days. 

Throughout  the  fast  following  submaintenance  rations  in  March  1924, 
the  carbon-dioxide  elimination  is  on  a  distinctly  lower  plane,  a  minimum 
of  40.7  gm.  being  found  with  steer  C  on  the  last  day  and  a  minimum  of 
44.3  gm.  with  steer  D  on  the  eighth  day.  With  the  two  younger  animals, 
steers  E  and  F,  which  fasted  following  submaintenance  feeding,  there  is 
essentially  a  continuous  decrease  as  long  as  the  fasts  lasted,  i.  e.,  for  4 
or  5  days. 

In  certain  experiments  food  was  given  immediately  after  the  fast,  and 
in  all  of  these  instances  the  carbon-dioxide  excretion  increased  appreciably, 
although  the  time  after  feeding  was  relatively  short  and  the  amount  of 
food  actually  eaten  was  small,  as  these  animals  were  very  deliberate  in 
their  first  feeding  after  a  prolonged  fast. 


Table  42.— Carbon-dioxide  elimination  before  and  during  fasts  of  6  to  U  days 
(Average  values  in  grams  per  half  hour) 


METABOLISM  DURING  FASTING 


163 


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Measurement  made  during  period  of  lying  and  standing 


164 


METABOLISM  OF  THE  FASTING  STEER 


In  general,  during  these  long  fasts,  the  carbon-dioxide  production  falls 
off  rapidly  during  the  first  three  or  four  days.  The  decrease  usually  con¬ 
tinues  until  the  end  of  the  fast  and  is  followed  by  a  rapid  rebound  after 
the  ingestion  of  even  small  amounts  of  relatively  indigestible  hay  or  meal 
mixtures.  In  the  fasts  at  a  submaintenance  level,  particularly  with  steers 
C  and  D,  the  total  amounts  of  carbon  dioxide  involved,  even  on  the  first 
day  of  fasting,  are  lower  than  in  any  of  the  other  fasts.  Indeed,  on  the 
second  day  in  the  March  fast  of  steer  C  a  value  of  42.8  gm.  per  half 
hour  was  noted,  which  is  lower  than  any  other  value  found  with  this  animal, 
even  at  the  end  of  the  14-day  fast.  On  the  other  hand,  the  submaintenance 
ration  did  not  affect  so  profoundly  the  carbon-dioxide  elimination  of  steer 
D,  for  it  is  not  until  the  eighth  day  of  his  fast  following  submaintenance 
rations  that  a  minimum  value  of  44.3  gm.  is  found,  which  is  lower  than 
that  found  in  any  of  the  fasts  following  maintenance  feeding.  This  differ¬ 
ence  in  the  metabolism  of  two  otherwise  presumably  comparable  animals 
will  be  noted  frequently  throughout  the  rest  of  this  discussion  of  the  gaseous 
metabolism  (see,  especially,  p.  180). 

In  a  series  of  2-day  and  3-day  fasts  with  steers  C  and  D  at  a  mainte¬ 
nance  level  of  nutrition,  carbon-dioxide  measurements  were  also  secured. 
These  are  recorded  in  Table  43.  In  the  case  of  steer  C,  it  is  seen  that  when 
he  had  been  25  to  26  hours  without  food  his  carbon-dioxide  production 
per  half  hour  was,  on  the  average  for  the  10  measurements  made,  71.0  gm. 
This  value  is  somewhat  lower  than  the  values  shown  in  Table  42  for  steer  C 
on  the  first  day  of  the  fasts  at  a  maintenance  level,  and  it  is  more  nearly 
in  line  with  the  average  value  to  be  found  for  this  animal  in  Table  42  on 
the  second  day  of  fasting.  With  steer  D,  the  average  value  for  the  10 
experiments  reported  in  Table  43  is  79.5  gm.,  materially  less  than  the  values 
recorded  in  his  case  for  the  first  day  of  fasting  in  Table  42. 

Table  43. — Carbon-dioxide  -production  of  steers  per  half  hour,  2J+  and  4-8  hours  after  food 

(Maintenance  level  of  nutrition) 


Steer  and  dates 
of  fasts 
(1923) 

Hours  without  food 

Steer  and  dates 
of  fasts 
(1923) 

Hours  without  food 

25  to  26 

47  to  50 

25  to  26 

47  to  50 

Steer  C: 

gm. 

gm. 

Steer  D: 

gm. 

grn. 

Jan.  4  and  5.  . . . 

66.6 

1  59.2 

Jan.  10  and  11.. .  . 

79.6 

1  64.8 

Jan.  22  and  23 ... . 

56.8 

62.8 

Jan.  18  and  19.. . . 

76.5 

53.1 

Jan.  29  and  30. . . . 

77.8 

43.1 

Jan.  26  and  27.. . . 

82.6 

50.8 

Feb.  6  and  7 ... . 

67.2 

65.9 

Feb.  2  and  3. .  .  . 

74.0 

59.6 

Feb.  12  and  13 ... . 

69.8 

61.7 

Feb.  9  and  10. . . . 

75.6 

67.3 

Feb.  19  and  20. . . . 

74.6 

73.0 

Feb.  15  and  16. . . . 

83.6 

85.6 

Mar.  2  and  3 .  .  .  . 

73.2 

59.3 

Feb.  23  and  24. . . . 

79.8 

73.7 

Mar.  9  and  10 ... . 

71.8 

69.0 

Mar.  6  and  7. . .  . 

80.2 

75.1 

Mar.  16  and  17 ... . 

71.9 

58.7 

Mar.  14  and  15. . . . 

79.7 

72.3 

Mar.  23  and  24 ...  . 

80.5 

65.2 

Mar.  21  and  22.. .  . 

83.7 

68.0 

Average . 

71.0 

61.8 

Average .... 

79.5 

67.0 

1  Determinations  made  72  hours  after  food  in  the  January  experiments  showed  a  carbon- 
dioxide  production  of  55.3  gm.  with  steer  C  and  54.5  gm.  with  steer  D. 


METABOLISM  DURING  FASTING 


165 


On  the  second  day  of  the  short  fasts,  when  the  steers  had  been  47  to  50 
hours  without  food,  the  average  carbon-dioxide  production  was  61.8  and 
67.0  gm.  per  half  hour  with  steers  C  and  D,  respectively,  values  more 
nearly  like  those  noted  on  the  second  day  of  the  longer  fasts. 

The  differences  noted  between  the  series  of  short  fasts  and  the  series  of 
longer  fasts  in  the  carbon-dioxide  production  on  the  first  day  of  fasting, 
and  the  general  differences  between  the  two  series  of  fasts,  are  excellent 
demonstrations  of  the  fact  that  the  carbon-dioxide  production  on  the  first 
day  of  fasting  is  so  irregular  as  to  make  its  use  as  an  index  of  heat-produc¬ 
tion  of  doubtful  value  without  careful  consideration  of  the  respiratory 
quotient.  The  respiratory  quotient  also  varies  on  the  first  day,  as  can  be 
seen  from  Table  .39,  page  157.  The  differences  noted  in  the  two  series  may 
in  part  be  explained  by  differences  in  prior  feed  conditions,  the  effect  of 
repeated  short  fasts,  and  indeed,  differences  in  environmental  temperature. 

Tabular  Presentation  of  Data  for  Long  and  Short  Fasts 

The  data  accumulated  in  this  fasting  research  were  so  extensive  that 
space  will  not  permit  of  publishing  all  the  details,  and  it  is  possible  to 
present  only  condensed  abstracts.  During  the  experimental  season  from 
December  1921  through  March  1924,  steers  C  and  D  fasted  at  intermittent 
intervals  for  periods  of.  from  2  to  14  days,  or  a  total  of  80  and  76  days, 
respectively.  The  pertinent  data  for  these  fasts  have  been  summarized 
in  Tables  44  and  45.  Similar  data  for  the  fasts  of  steers  E  and  F  in  Feb¬ 
ruary  1924  have  been  summarized  in  Table  46.  The  gaseous-metabolism 
measurements  reported  for  all  these  fasting  days  were  obtained  22  hours 
or  more  after  the  last  food  was  given,  and  in  every  case  represent  average 
values  for  three  or  four,  well-agreeing  periods,  each  of  30  minutes’  duration. 
In  all  instances  the  animal  was  in  the  standing  position,  unless  otherwise 
indicated  in  the  tables.  The  accuracy  of  the  respiration  chamber  was 
frequently  controlled  throughout  this  time  by  introducing  and  recovering 
known  amounts  of  carbon  dioxide.  (See  p.  36.) 

The  live  weight  reported  for  the  first  day  of  fasting,  i.  e.,  when  the 
animal  had  been  for  24  hours  without  food,  represents  an  average  weight 
based  upon  the  weight  on  the  given  date  and  the  weights  for  6  days  pre¬ 
ceding  or  for  as  many  days  preceding  up  to  six  for  which  live  weights  were 
available.  For  each  fasting  day  after  the  first  the  weights  represent  indi¬ 
vidual  weights  obtained  at  2  p.  m.  of  the  given  date,  in  all  cases  except  the 
fasts  in  March  1924,  with  steers  C  and  D,  when  the  weights  were  recorded 
at  7  a.  m.  because  the  24-hour  periods  began  and  ended  at  that  time.  The 
heart-rates  recorded  in  these  tables  represent  those  records  secured  nearest 
to  the  time  of  the  respiration  experiment,  either  shortly  before  or  shortly 
after  the  experiment.  The  values  for  the  insensible  perspiration  and  for 
the  stall  temperature  are  for  the  24-hour  periods  from  2  p.  m.  of  the 
preceding  date  to  2  p.  m.  of  the  given  date  in  all  fasts  except  those  of  steers 
C  and  D  in  March  1924,  when  the  24-hour  periods  began  at  7  a.  m.  The 
respiration  experiments  were  usually  made  during  the  morning  of  the  given 
date,  so  that  the  values  for  insensible  perspiration  and  similarly  for  the 
stall  temperature  represent  essentially  the  24-hour  period  preceding  the 


166 


METABOLISM  OF  THE  FASTING  STEER 


Table  44. — Metabolism  of  steer  C  when  fasting  at  different  levels  of  nutrition 


Insen- 

Stall 

temper¬ 

ature 

Hours 

Average 

chamber 

temper¬ 

ature 

Carbon 

Respir¬ 

atory 

quo¬ 

tient 

Heat  produced  per  24  hours 

Date 

Live 

weight 

rate 

per 

minute 

sible 
loss 
per  24 
hours 

food  to 
beginning 
of  experi¬ 
ment 

pro¬ 
duced 
per  half 
hour 

Total 

Per 

500  kg. 

Per 
sq.  m. 

1921 

Dec.  7.... 

kg. 

584.8 

44 

kg. 

4.0 

°C. 

5 

28 

°C. 

gm. 

76.1 

(0.82) 

cal. 

10,900 

cal. 

9,300 

cal. 

1,880 

Dec. 

8.  .  .  . 

561.4 

34 

3.4 

5 

52 

17.0 

62.1 

(  .76) 

9,500 

8,500 

1,680 

Dec. 

9. .  .  . 

550.0 

32 

1.6 

15 

76 

20.6 

55.1 

(  .73) 

8,700 

7,900 

1,560 

Dec. 

10. . . . 

543.4 

36 

3.2 

20 

97 

19.3 

52.8 

(  -72) 

8,400 

7,700 

1,520 

Dec. 

11. . . . 

543.4 

2.8 

18 

121 

19.3 

51.4 

(  .71) 

8,300 

7,600 

1,500 

Dec. 

12. . . . 

538.2 

2.2 

17 

146 

18.8 

50.3 

(  .70) 

8,200 

7,600 

1,490 

Dec. 

13.... 

533.2 

2.2 

20 

169 

23.0 

49.6 

(  .70) 

8,100 

7,600 

1,480 

1922 

Jan.  5. . . . 

588.2 

48 

11.6 

20 

27 

24.3 

79.4 

(  -82) 

11,400 

9,700 

1,960 

Jan. 

6.  . .  . 

570.6 

38 

7.0 

20 

51 

21.9 

70.8 

(  .76) 

10,800 

9,500 

1,890 

Jan. 

7.  .  .  . 

564.4 

38 

4.8 

20 

75 

20.0 

60.9 

(  -73) 

9,600 

8,500 

1,690 

Jan. 

8. . . . 

555.6 

36 

5.4 

21 

97 

21.5 

52.6 

(  .72) 

8,400 

7,600 

1,500 

Jan. 

9.  .  .  . 

549.0 

38 

3.6 

24 

123 

24.8 

55.0 

(  -71) 

8,900 

8,100 

1,600 

Jan. 

10. . . . 

548.2 

38 

4.2 

20 

147 

21.3 

51.6 

(  .70) 

8,400 

7,700 

1,510 

Jan. 

11.... 

539.6 

36 

4.0 

20 

171 

IS. 7 

51.4 

(  .70) 

8,400 

7,800 

1,520 

Jan. 

12.... 

536.2 

30 

3.6 

21 

196 

20.8 

47.3 

(  .70) 

7,700 

7,200 

1,400 

Jan. 

13.... 

538.4 

34 

3.6 

23 

219 

22.9 

51.0 

(  .70) 

8,300 

7,700 

1,510 

Jan. 

14.... 

531.8 

38 

4.2 

23 

243 

23.7 

52.9 

(  .70) 

8,700 

8,200 

1,590 

Apr. 

18.... 

605.6 

42 

12.6 

20 

28 

25.4 

79.6 

.89 

10,700 

8,800 

1,800 

Apr. 

19. . . . 

593.6 

38 

6.0 

20 

51 

23.9 

59.5 

.82 

8,600 

7,200 

1,470 

Apr. 

20.... 

581.0 

38 

7.2 

20 

75 

21.4 

56.0 

(  .73) 

8,800 

7,600 

1,530 

Apr. 

21.... 

571.4 

38 

2.4 

15 

99 

19.3 

52.4 

.73 

8,300 

7,300 

1,450 

Apr. 

22.... 

567.0 

34 

3.2 

20 

123 

19.7 

51.6 

.73 

8,100 

7,100 

1,420 

Apr. 

23.... 

565.2 

30 

4.2 

22 

144 

23.3 

51.8 

f  .70] 

8,500 

7,500 

1,500 

Apr. 

24 ...  . 

557.2 

30 

3.8 

22 

171 

22.9 

48.0 

(  .70) 

7,900 

7,100 

1,410 

Apr. 

25.... 

552.8 

32 

3.6 

22 

195 

23.4 

51.1 

(  .70) 

8,400 

7,600 

1,500 

Apr. 

26.... 

548.6 

34 

4.0 

23 

219 

24.3 

51.1 

(  .70) 

8,400 

7,700 

1,510 

Apr. 

27.... 

545.6 

32 

4.8 

20 

243 

19.9 

47.6 

(  .70) 

7,800 

7,100 

1,410 

Apr. 

28.... 

541.6 

30 

2.0 

22 

267 

20.8 

45.9 

(  .70) 

7,500 

6,900 

1,360 

Apr. 

29.... 

535.4 

32 

3.0 

21 

291 

22.1 

46.9 

.70 

7,700 

7,200 

1,400 

Apr. 

30. . . . 

531.2 

32 

3.6 

21 

312 

22.3 

44.9 

(  .70) 

7,300 

6,900 

1,340 

May 

1.... 

529.4 

30 

3.4 

21 

336 

22.4 

43.6 

(  -70) 

7,100 

6,700 

1,300 

June 

2 

602.0 

40 

10.8 

23 

22 

26.0 

80.6 

.85 

11,300 

9,400 

1,920 

June 

3.... 

584.2 

40 

5.2 

22 

46 

23.4 

63.8 

.75 

9,800 

8,400 

1,690 

June 

4. . .  . 

567.6 

44 

5.6 

23 

67 

25.7 

52.6 

.73 

8,300 

7,300 

1,460 

June 

5.... 

558.2 

32 

4.6 

25 

94 

26.6 

52.4 

.70 

8,600 

7,700 

1,530 

June 

7.... 

548.2 

32 

7.8 

26 

143 

29.0 

53.9 

[  .70] 

8,800 

8,000 

1,580 

Nov. 

7.... 

672.4 

> 

48 

12.6 

26 

25.4 

*84.3 

.74 

i 13,200 

i  9,800 

»  2,090 

Nov. 

8. . 

654.4 

38 

7.8 

50 

24.3 

1  72. 6 

.76 

111,100 

18,500 

1 1,780 

Nov. 

9.  . . . 

651.6 

44 

8.0 

73 

26.7 

i  66.4 

.73 

1 10,500 

18,100 

1 1,690 

Nov. 

10.... 

638.6 

40 

7.2 

98 

26.4 

158.1 

(  .72) 

i  9,300 

17,300 

i  1,520 

Nov. 

11.... 

631.2 

40 

3.0 

122 

16.8 

1  59.8 

.72 

19,400 

17,400 

1 1,550 

Nov. 

14. . . . 

625.0 

36 

2.0 

192 

13.4 

58.5 

[  .70] 

9,600 

7,700 

1,590 

Nov. 

15.... 

617.2 

38 

4.0 

218 

27.8 

61.9 

l  .70] 

10,100 

8,200 

1,680 

1923 

Jan.  4 _ 

686.2 

38 

6.4 

6 

25 

6.3 

66.6 

.83 

9,500 

6,900 

1,480 

Jan. 

5.... 

683.0 

36 

3.0 

9 

49 

7.7 

59.2 

.73 

9,300 

6,800 

1,460 

Jan. 

6.... 

680.4 

36 

2.8 

12 

73 

9.6 

55.3 

.72 

8,800 

6,500 

1,380 

Jan. 

22.... 

686.4 

40 

10.8 

28 

25 

26.7 

56.9 

.83 

8,100 

5,900 

1,260 

Jan. 

22. . . . 

686.4 

36 

10.8 

28 

30 

27.9 

56.8 

.83 

8,100 

5,900 

1,260 

Jan. 

23.... 

683.0 

34 

4.4 

7 

49 

-1.9 

62.8 

.76 

9,600 

7,000 

1,500 

Jan. 

29. . . . 

694.2 

40 

4.8 

8 

25 

2.9 

77.8 

.82 

11,200 

8,100 

1,740 

Jan. 

30.... 

691.4 

36 

5.0 

25 

49 

24.9 

43.1 

.73 

6,800 

4,900 

1,060 

% 

Feb. 

6.... 

693.2 

42 

5.2 

6 

25 

2.6 

67.2 

.83 

9,600 

6,900 

1,490 

Feb. 

7.... 

691.0 

34 

2.8 

5 

49 

2.0 

65.9 

.73 

10,400 

7,500 

1,610 

1  Steer  standing  and  lying. 


METABOLISM  DURING  FASTING 


167 


Table  44. 


Date 


1923 
'eb.  12. 
'eb.  13. 

eb.  19. 
eb.  20. 

far.  2. 
far.  3. 

[ar.  9 . 
far.  10. 

!ar.  16. . 
'ar.  17.. 

ar.  23. . 
ar.  24. . 


■Metabolism  of  steer  C  when  fasting  at  different  levels  of  nutrition- Continued 


DV. 

5V. 

)V. 

)V. 


6. 

7. 

8. 

9 

>v.  10. 
1924 
ir.  4. 
»r. 
ir. 
ir. 
ir. 
ir. 


5. , 

6. . 

7.. 

8.. 
9. . 

ir.  10. . 
ir.  11.. 
>r.  12.. 
r.  13.. 

v.  13s  . 


Live 

weight 

Heart- 

rate 

per 

minute 

Insen¬ 

sible 

Stall 

Hours 

without 

Average 

Carbon 

dioxide 

Respir- 

Heat  produced  per  24  hours 

loss 
per  24 
hours 

temper¬ 

ature 

food  to 
beginning 
of  experi¬ 
ment 

chambe 

temper¬ 

ature 

r  pro¬ 
duced 
per  half 
hour 

atory 

quo¬ 

tient 

Total 

Per 

500  kg. 

Per 
sq.  m. 

kg. 

..  689.6 

. .  686.6 

35 

40 

kg. 

4.6 

2.8 

°C. 

8 

8 

25 

49 

°C. 

3.9 

1.7 

gm. 

69.8 

61.7 

0.84 

.74 

cal. 

9,800 

9,600 

cal. 

7,100 

7,000 

cal. 

1,520 

1,500 

. .  689.8 

.  687.2 

40 

42 

3.4 

3.6 

4 

0 

25 

49 

2.5 

-1.0 

74.6 

73.0 

.82 

.70 

10,700 

11,900 

7,800 

8,700 

1,660 

1,860 

.  694.8 

.  692.4 

40 

48 

6.2 

3.8 

12 

14 

25 

49 

7.3 

10.9 

73.2 

59.3 

.83 

.79 

10,400 

8,800 

7,500 

6,400 

1,610 

1,370 

.  694.0 

.  691.8 

34 

36 

4.6 

3.0 

4 

6 

25 

49 

4.3 

2.0 

71.8 

69.0 

.84 

.77 

10,100 

10,400 

7,300 

7,500 

1,570 

1,610 

.  698.6 

.  695.6 

42 

34 

5.2 

3.2 

8 

8 

26 

50 

11.9 

24.4 

71.9 

58.7 

.80 

.77 

10,500 

8,900 

7,500 

6,400 

1,620 

1,380 

.  681.4 

.  676.8 

40 

40 

14.8 

8.8 

26 

22 

25 

49 

29.2 

13.5 

80.5 

65.2 

.86 

.79 

11,200 

9,700 

8,200 

7,200 

1,760 

1,530 

.  694.0 

46 

6.2 

42 

65 

89 

113 

1  37 

21.5 

81.7 

67.7 
59.3 

.79 

.74 

.73 

.72 

.70 

12,100 

8,700 

.  675.8 

44 

3.8 

1,880 

.  665.2 

48 

3.0 

18.5 

22.6 

10, 600 

7,800 

1,670 

656.4 

40 

2.8 

9,400 

7,100 

1,500 

(656.4) 

34 

63.5 

10,000 

7,600 

1,610 

10,400 

7,900 

1,670 

636.6 

36 

14 

16 

16 

16 

14 

16 

18 

14 

16 

16 

12.0 

11.1 

15.2 
13.1 

12.3 

21.3 

17.7 

10.7 
14.0 
17.5 

55.1 

42.8 

43.8 

44.4 

44.5 

44.2 

45.8 

44.9 

44.7 

40.7 

.82 

.74 

.71 

.70 

.70 

.71 

.70 

.70 

.71 

.70 

7,900 

6,700 

7,100 

7,300 

7,300 

7,100 

7,500 

7,300 

7,200 

6,700 

627.2 

619.6 

613.4 

609.8 

604.8 

600.4 
597.0 

593.8 

589.6 

30 

40 

28 

28 

24 

25 

28 

24 

34 

1.4 

2.6 

1.8 

1.4 

3.8 

2.0 

2.2 

2.2 

2.0 

49 

73 

98 

122 

146 

170 

195 

219 

241 

6,200 

5,300 

5,700 

6,000 

6,000 

5,900 

6,200 

6,100 

6,100 

5,700 

1,290 

1,110 

1,180 

1,220 

1,230 

1,200 

1,270 

1,240 

1,230 

1,150 

764.2 

54 

9.2 

45 

24.4 

>77.9 

.76  > 

11,900 

>7,800 

>1,740 

*  Steer  not  m  normal  condition;  vomited  while  in  respiration  chamber. 

measurement  of  the  gaseous  metabolism.  The  average  chamber  tempera¬ 
ture  indicates  the  temperature  existing  during  the  3  or  4  half-hour  periods 
when  the  animal  was  inside  the  respiration  chamber.  The  actual  number 
of  hours  elapsing  between  the  last  ingestion  of  food  and  the  beginning  of 

eXperim1e^t  *s  Sivenr  for  each  date,  rather  than  the  number 
oi  days  that  the  animal  had  been  fasting. 

The  respiratory  quotients  in  the  fasts  in  April  1922  and  in  the  subsequent 
fasts  were  usually  actually  determined  with  the  Carpenter  gas-analysis 
apparatus,  but  no  determinations  were  made  for  the  fasts  in  December  1921 
““  Jan"f  S'  W22,  and  respiratory  quotients  had  to  be  assumed  in  these 
bT'  /  resPlratory  quotients  not  actually  determined  but  assumed  are 
inclosed  in  parentheses.  Those  inclosed  in  square  brackets  are  based  upon 
quotients^  which  were  actually  determined  but  which  were  somewhat  below 

f°r  purposfs  of  imputing  the  heat-production  a  quotient  of 
u.70  has  been  assumed  in  these  cases.  Since  the  fasts  of  steers  C  and  D  in 
December  1921  and  January  1922  were  made  at  a  maintenance  level  of 


168 


METABOLISM  OF  THE  FASTING  STEER 


Table  45. — Metabolism  of  steer  D  when  fasting  at  different  levels  of  nutrition 


Date 

Live 

weight 

Heart- 

rate 

per 

minute 

Insen¬ 
sible 
loss 
per  24 
hours 

1921 

kg. 

kg. 

Dec.  7 ...  ■ 

601.4 

36 

4.4 

Dec.  8 - 

582.6 

36 

3.2 

Dec.  9  .  . .  . 

576.4 

36 

3.2 

Dec.  10 ...  . 

576.8 

36 

3.8 

Dec.  11 - 

Dec.  12 _ 

569.8 

3.6 

563.6 

2.4 

Dec.  13 - 

566.6 

3.4 

1922 

Jan.  5  .  .  .  . 

607.0 

48 

11.4 

Jan.  6  .  .  .  . 

593.6 

40 

7.0 

Jan.  7  ...  . 

591.2 

40 

5.0 

Jan.  8  .  .  .  . 

578.8 

38 

6.8 

Jan.  9  .  .  .  . 

586.2 

36 

5.2 

Jan.  10 ...  . 

578.0 

32 

4.0 

Jan.  11 ...  . 

578.4 

36 

3.0 

Jan.  12  ...  . 

571.0 

36 

4.0 

Jan.  13  ...  . 

568.0 

28 

4.4 

Jan.  14 ... . 

570.4 

27 

4.0 

Apr.  18 ...  . 

621.0 

40 

12.4 

Apr.  19 ...  . 

608.6 

36 

4.2 

Apr.  20 ...  . 

599.4 

34 

5.2 

Apr.  21 _ 

593.4 

42 

4.2 

Apr.  22 ...  . 

586.6 

42 

3.0 

Apr.  23 ...  . 

585.8 

38 

3.8 

Apr.  24 ... . 

578.8 

32 

3.6 

Apr.  25 ...  . 

578.6 

38 

3.8 

Apr.  26  ...  . 

575.6 

30 

4.6 

Apr.  27 ...  . 

571.8 

36 

3.4 

Apr.  28 ... . 

565.0 

36 

3.2 

Apr.  29 ...  . 

563.8 

32 

2.8 

Apr.  30 ...  . 

557.2 

34 

4.2 

May  1 .  .  .  . 

551.8 

32 

2.8 

June  2  .  .  .  . 

610.8 

54 

9.2 

June  3 . . . . 

593.0 

52 

6.2 

June  4 . . . . 

585.8 

48 

6.2 

June  5 . . . . 

575.4 

48 

5.2 

June  6  .  .  . . 

577.8 

46 

8.0 

Nov.  8 .  .  .  . 

661.2 

48 

9.4 

Nov.  9  .  .  .  . 

649.8 

48 

8.8 

Nov.  10 _ 

640.4 

48 

8.6 

Nov.  12 ...  . 

645.0 

42 

3.0 

Nov.  13 ... . 

638.6 

40 

2.6 

1923 

Jan.  10 ...  . 

688.6 

48 

6.4 

Jan.  11 ...  . 

685.  S 

42 

3.4 

Jan.  12 ... . 

683.8 

38 

3.0 

Jan.  18 ...  . 

690.0 

42 

6.0 

Jan.  19 ... . 

686.2 

48 

8.2 

Jan.  26 ...  . 

688.6 

44 

5.8 

Jan.  27  ... . 

685.8 

38 

6.8 

Feb.  2 _ 

681.4 

44 

6.0 

Feb.  3  .  . . . 

677.4 

40 

3.4 

Feb.  9 _ 

686.4 

40 

5.0 

Feb.  10 _ 

683.0 

42 

3.2 

Feb.  15... 

695.4 

40 

4.6 

Feb.  16 .  . . 

691.0 

76 

2.2 

Stall 

temper¬ 

ature 

Hours 
without 
food  to 
beginning 
of  experi¬ 
ment 

Average 

chamber 

temper¬ 

ature 

Carbon 
dioxide 
pro¬ 
duced 
per  half 
hour 

°C. 

5 

30 

°C. 

22.0 

gm. 

85.6 

5 

54 

19.9 

63.8 

15 

78 

22.3 

61.3 

20 

99 

23.7 

58. 1 

18 

123 

23.4 

56.1 

17 

148 

23.1 

54.1 

20 

172 

25.6 

53.0 

20 

29 

22.7 

84.9 

20 

53 

21.2 

67.3 

20 

77 

21.9 

60.3 

21 

99 

24.5 

56.3 

24 

125 

23.6 

56.3 

20 

149 

21.7 

52.4 

20 

173 

23.0 

53.9 

21 

197 

23.7 

49.6 

23 

221 

22.4 

50.6 

23 

245 

23.4 

51.3 

20 

32 

25.8 

83.4 

20 

56 

24.5 

67.8 

20 

80 

22.0 

59.5 

20 

104 

20.1 

54.4 

15 

128 

21.6 

53.0 

20 

146 

24.0 

51.9 

22 

173 

24.1 

50.8 

22 

200 

24.3 

51.0 

22 

221 

26.5 

49.8 

23 

245 

21.0 

47.4 

20 

272 

20.3 

51.0 

22 

296 

24.1 

48.0 

21 

315 

23.0 

47.5 

21 

339 

24.1 

47.4 

23 

31 

27.3 

83.7 

22 

55 

25.8 

67.7 

23 

74 

28.8 

64.1 

25 

103 

31.5 

57.5 

27 

121 

29.0 

61.2 

54 

26.4 

80.7 

78 

26.7 

71.3 

102 

26.5 

69.8 

144 

16.2 

63.1 

16S 

9.3 

60.0 

13 

26 

7.0 

79.6 

9 

49 

7.0 

64.8 

10 

74 

2.7 

54.5 

12 

25 

3.4 

76.5 

28 

49 

28.2 

53.1 

11 

26 

8.8 

82.6 

26 

49 

28.3 

50.8 

23 

25 

27.9 

74.0 

12 

47 

7.3 

59.6 

8 

25 

8.6 

75.6 

10 

49 

5.7 

67.3 

-  3 

25 

-1.6 

83.6 

-  3 

49 

-7.5 

85.6 

Respir- 

atory 

quo¬ 

tient 

Heat  produced  per  24  hours 

Total 

Per 

500  kg. 

Per 
sq.  m. 

cal. 

cal. 

cal. 

(0 

.82) 

12,300 

10,200 

2,080 

( 

.76) 

9,700 

8,300 

1,680 

( 

.73) 

9,700 

8,400 

1,690 

( 

.72) 

9,300 

8,100 

1,620 

( 

.71) 

9,100 

8,000 

1,600 

( 

.70) 

8,800 

7,900 

1,550 

( 

.70) 

8,700 

7,700 

1,530 

( 

.82) 

12,200 

10,000 

2,060 

( 

.76) 

10,300 

8,700 

1,760 

( 

.73) 

9,500 

8,000 

1,630 

( 

.72) 

9,000 

7,800 

1,560 

( 

.71) 

9,100 

7,800 

1,570 

( 

.70) 

8,600 

7,400 

1,500 

( 

.70) 

8,800 

7,600 

1,530 

( 

.70) 

8,100 

7,100 

1,420 

( 

.70) 

8,300 

7,300 

1,460 

( 

.70) 

8,400 

7,400 

1,470 

.97 

10,500 

8,500 

1,740 

.83 

9,700 

8,000 

1,630 

.75 

9,200 

7,700 

1,560 

.75 

8,400 

7,100 

1,440 

.74 

8,300 

7,100 

1,430 

.73 

8,200 

7,000 

1,410 

( 

.72) 

8,100 

7,000 

1,410 

( 

.71) 

8,200 

7,100 

1,420 

( 

.70) 

8,100 

7,000 

1,410 

( 

.70) 

7,800 

6.S00 

1,360 

( 

.70) 

8,300 

7,300 

1,460 

( 

.70) 

7,900 

7,000 

1,390 

( 

.70) 

7,800 

7,000 

1,390 

( 

.70) 

7,800 

7,100 

1,400 

.77 

12,700 

10,400 

2,130 

.73 

10,700 

9,000 

1,830 

.70 

10,500 

9,000 

1,810 

.71 

9,300 

8,100 

1,620 

[ 

.70] 

10,000 

8,700 

1,740 

.72 

12,900 

9,800 

2,060 

.71 

11,500 

8,800 

1,860 

( 

.71) 

11,300 

8,800 

1,840 

( 

.70) 

10,300 

8,000 

1,670 

( 

.70) 

9,800 

7,700 

1,600 

.83 

11,300 

8,200 

1,760 

.73 

10,200 

7,400 

1,590 

.70 

8,900 

6,500 

1,390 

.81 

11,100 

8,000 

1,730 

.74 

8,300 

6,000 

1,290 

.82 

11,900 

8,600 

1,850 

.78 

7,600 

5,500 

1,190 

.86 

10,300 

7,600 

1,610 

.75 

9,200 

6,800 

1,450 

.78 

11,300 

8,200 

1,760 

.77 

10,200 

7,500 

1,600 

.82 

12,000 

8,600 

1,860 

.75 

13,200 

9,600 

2,050 

METABOLISM  DURING  FASTING 


169 


Table  45.  Metabolism,  of  steer  D  when  fasting  at  different  levels  of  nutrition — Continued 


Date 

Live 

weight 

Heart- 

rate 

per 

minute 

Insen¬ 
sible 
loss 
per  24 
hours 

Stall 

temper¬ 

ature 

Hours 
without 
food  to 
beginning 
of  experi¬ 
ment 

Average 

chamber 

temper¬ 

ature 

Carbon 
dioxide 
pro¬ 
duced 
per  half 
hour 

Respir¬ 

atory 

quo¬ 

tient 

Heat  produced  per  24  hours . 

Total 

Per 

500  kg. 

Per 
aq.  m. 

1923 

kg. 

kg. 

°C. 

°C. 

gm. 

cal. 

Feb.  23 ... . 

691.4 

54 

4.4 

+  2 

25 

3.6 

79.8 

.83 

11,400 

8,200 

1,770 

Feb.  24 ... . 

688.4 

48 

3.2 

-  2 

49 

0.2 

73.7 

.73 

11,600 

8,400 

U810 

Mar.  6 . . . . 

690.6 

64 

3.8 

4 

25 

2.1 

80.2 

.83 

11,400 

8,300 

1,770 

Mar.  7 ... . 

687.6 

44 

3.8 

3 

50 

0.3 

75.1 

(  .75) 

11,600 

8,400 

1,810 

Mar.  14 . . . 

695.4 

48 

6.0 

7 

25 

10.5 

79.7 

.84 

11,200 

8,100 

1,730 

Mar.  15 .  . . 

692.6 

38 

3.8 

5 

50 

22.8 

72.3 

.79 

10,700 

7,700 

U660 

Mar.  21 _ 

693.2 

52 

14.2 

24 

26 

12.6 

83.7 

.86 

11,600 

8,400 

1,800 

Mar.  22 _ 

688.4 

38 

10.4 

27 

49 

29.0 

68.0 

.76 

10,400 

7,600 

1  i  620 

'iov.  5 _ 

707.0 

60 

22 

22.1 

117.4 

.86 

16,300 

12,000 

2,490 

'Jov.  6 . . . . 

669.6 

72 

11.6 

46 

21.2 

86.2 

.76 

13,200 

9,900 

2,090 

\7ov.  7 .  . . 

653.6 

52 

5.0 

70 

19.9 

71.4 

.72 

11,400 

8,700 

1,830 

'lov.  8 .  . . . 

658.8 

52 

4.8 

94 

15.2 

70.4 

.72 

11,200 

8,500 

1,790 

'lov.  9 . . . . 
1924 

651.4 

64 

4.0 

116 

23.2 

62.9 

.71 

10,200 

7,800 

1,650 

Mar.  4 . .  . . 

624.0 

44 

14 

32 

13.6 

67.9 

.73 

10,700 

8,600 

1,770 

Mar.  5 . . . . 

610.0 

32 

3.4 

16 

52 

14.9 

59.3 

.73 

9,400 

7,700 

1,580 

Mar,  6 .  . . . 

602.2 

32 

2.8 

16 

77 

15.9 

53.8 

.70 

8,800 

7,300 

1,490 

Mar.  7 ... . 

606.4 

36 

2.8 

16 

102 

11.9 

53.0 

.70 

8,700 

7,200 

1,470 

Mar.  8 .  . . . 

598.8 

48 

2.2 

14 

126 

11.7 

49.5 

(  .70) 

8,100 

6,800 

1,380 

*lar.  9 .  . . . 

593.4 

50 

2.8 

16 

149 

19.3 

55.7 

(  .70) 

9,100 

7,700 

1,560 

Mar.  10 ... . 

596.4 

34 

4.0 

18 

174 

15.6 

51.4 

.70 

8,400 

7,000 

1 ,430 

Mar.  11.... 

590.6 

36 

2.2 

14 

198 

13.8 

44.3 

.70 

7,200 

6,100 

1,230 

Mar.  12 ... . 

587.2 

34 

1.4 

16 

228 

16.2 

45.0 

.71 

7,300 

6,200 

1,260 

Table  46.— Metabolism  of  steers  E  and  F  when  fasting  after  submaintenance  feeding 


Steer 

and 

date 

(1924) 

Live 

weight 

Heart- 

Insen¬ 

sible 

Stall 

Hours 

without 

Average 

Carbon 

dioxide 

Respir- 

Heat  produced  per  24  hours 

rate 

per 

minute 

loss 
per  24 
hours 

temper¬ 

ature 

food  to 
beginning 
of  experi¬ 
ment 

chamber 

temper¬ 

ature 

pro¬ 
duced 
per  half 
hour 

atory 

quo¬ 

tient 

Total 

Per 

500  kg. 

Per 
sq.  m. 

teer  E: 

Feb.  13... 
Feb.  14... 
Feb.  15... 
Feb.  16... 
teer  F: 

Feb.  13... 
Feb.  14. . . 
Feb.  15... 
Feb.  17... 

kg. 

247.4 
238.6 
235.0 
234.0 

273.0 

263.0 

257.4 
254.2 

40 

36 

34 

36 

40 

36 

38 

34 

kg. 

3.0 

1.8 

2.0 

2.6 

3.8 

1.2 

2.2 

2.2 

°C. 

16 

15 

16 

15 

16 

15 

16 

14 

27 

51 

75 

98 

32 

55 

79 

122 

°C. 

15.5 
14.7 

17.6 

14.6 

17.4 

17.0 

19.0 

21.1 

gm. 

38.0 

35.0 

30.9 
31.7 

37.5 

36.4 

36.1 

33.9 

0.84 

.72 

I  .70] 

[  -70] 

.78 
.73 
[  -70] 
.72 

cal. 

5,400 

5,600 

5,100 

5,200 

5,600 

5,700 

5,900 

5,400 

cal. 

10,900 

11,700 

10,900 

11,100 

10,300 

10,800 

11,500 

10,600 

cal. 

1,600 

1,690 

1,550 

1,590 

1,560 

1,620 

1,700 

1,570 

nutrition,  the  assumptions  for  the  respiratory  quotients  used  in  computing 
the  heat-production  for  these  fasts  were  based  upon  respiratory  quotients 
obtained  during  the  fasts  in  April  and  June  1922  and  the  series  of  short  fasts 
in  1923,  all  of  which  also  followed  maintenance  feeding. 

The  computations  of  the  heat-production  were  carried  out  as  described 
on  page  148,  the  values  for  the  body-surface  being  derived  from  the  curve 
given  in  Fig.  8,  page  155. 


170 


METABOLISM  OF  THE  FASTING  STEER 


The  feed-level  prior  to  each  of  the  fasts  reported  in  Tables  44,  45,  and  46 
has  been  indicated  in  Table  47.  The  last  individual  feed  before  each  fast 
is  given  in  Table  11,  page  53. 


Table  47. — Feed-level  prior  to  long  and  short  fasts 


Steer  and  dates 

Per  day 

Hay 

Meal 

Steers  C  and  D: 

kg. 

kg. 

Nov.  26,  1921  to  Dec.  6,  192U . 

9.0 

1.36 

Dec.  27,  1921  Jan.  4,  1922  . 

7.5 

6.00 

Mar.  31,  1922  Apr.  17,  1922 . 

9.0 

3.00 

May  9,  1922  June  1,  1922 . 

9.0 

4.00 

June  10,  1922  Nov.  6,  1922 . 

Pasture 

Nov.  20,  1922  Mar.  27,  1923 . 

9.0 

2.00 

June  23,  1923  Nov.  4,  1923 . 

Pasture 

Dec.  21,  1923  Mar.  3,  1924 . 

4.5 

Steer  C: 

May  19,  1924  Nov.  11,  1924 . 

Pasture 

Steers  E  and  F: 

Dec.  18,  1923  Feb.  12,  1924 . 

2.5 

*0.30 

1  Steers  C  and  D  were  purchased  Oct.  26,  1921;  fed  hay  ad  libitum 
and  3  kg.  meal  until  Nov.  26,  1921. 

2  Meal  ration  reduced  to  100  gm.  on  Jan.  28,  1924. 


This  tabular  presentation  of  the  data  secured  in  the  series  of  long  and 
short  fasts  is  specifically  for  the  purpose  of  accurate  recording  of  results. 
The  large  number  of  experiments  and  the  length  of  the  tables  make  dis¬ 
cussion  of  each  individual  experiment  based  upon  these  tables  somewhat 
difficult.  For  this  reason  only  the  most  general  features  will  be  brought 
out  at  this  point,  and  the  more  critical  discussion  will  be  based  upon  the 
values  for  heat-production,  which  will  be  summarized  in  tabular  form  to 
show  the  course  of  the  metabolism  during  each  fast  and  which  will  enable 
the  comparison  of  one  fast  with  another  and  of  one  animal  with  another 
(see  Tables  48  to  51,  pp.  173  to  181). 

A  general  inspection  of  Tables  44,  45,  and  46  shows  that  as  the  fast 
progresses  there  is  a  decrease  in  all  the  factors  measured,  the  live  weight, 
the  heart-rate,  the  insensible  perspiration,  the  carbon-dioxide  production, 
the  respiratory  quotient,  and  also  the  computed  heat-production. 

The  fasts  varied  in  one  striking  particular,  that  is,  in  the  previous  state 
of  nutrition  of  the  animal.  Thus,  the  two  November  fasts  of  steers  C  and 
D  followed  pasture  feeding,  the  fasts  in  March  1924,  with  steers  C  and  D, 
and  in  February  1924,  with  steers  E  and  F,  followed  submaintenance  feed¬ 
ing,  and  all  of  the  other  fasts  followed  essentially  maintenance  feeding.  In 
most  of  the  fasts  of  5  to  14  days’  duration  the  chamber  temperature  did  not 
undergo  extreme  changes  during  any  one  fast.  The  range  in  temperatures 
was  from  about  15°  to  30°  C.,  but  a  large  proportion  of  the  experiments 
were  made  at  about  20°  C.  Occasionally  low  temperatures  are  recorded, 
however,  as,  for  instance,  on  November  13,  1922,  with  steer  D.  In  the 
series  of  short  fasts  in  1923  pronounced  differences  in  the  temperature  of 


METABOLISM  DURING  FASTING 


171 


the  chamber  were  designedly  made.  In  any  consideration  of  the  figures, 
therefore,  one  must  continually  bear  in  mind  the  environmental  tempera¬ 
ture  at  which  the  experiments  were  made  and  particularly  the  previous 
state  of  nutrition  of  the  animals. 

The  two  large,  mature  animals,  C  and  D,  were  subjected  to  exactly  the 
same  conditions  as  to  previous  state  of  nutrition  and  environmental  tem¬ 
perature,  in  order  that  they  might  be  as  nearly  as  possible  physiological 
duplicates,  as  were  steers  A  and  B  in  our  earlier  study  of  undernutrition. 
To  introduce  the  factor  of  immaturity  and  growth,  the  two  younger  and 
smaller  steers,  E  and  F,  were  studied.  Obviously,  a  direct  comparison  can 
not  be  made  between  the  values  obtained  with  these  two  steers  and  those 
obtained  with  steers  C  and  D  without  taking  into  consideration  not  only 
the  previous  state  of  nutrition  and  the  environmental  temperature,  but 
likewise  the  age  and  weight  of  the  animals. 

Course  of  the  Heat-production  During  Fasts  of  5  to  14  Days,  at  Different  Levels 

of  Nutrition 

The  chief  index  of  vital  activity  and  the  one  factor  above  all  others 
which  one  would  expect  to  be  affected  by  the  lack  of  food  is  the  general 
metabolism,  particularly  the  heat-production.  The  excretion  of  carbon 
dioxide  and  certain  physiological  factors,  such  as  heart-rate  and  respiration- 
rate,  have  already  been  considered  in  a  general  way.  The  clearest  cut 
evidence  as  to  the  degree  of  vital  activity,  however,  is  to  be  found  in  the 
computed  heat-production.  The  data  for  the  fasting  experiments  permit 
treatment  in  a  variety  of  ways.  If  only  one  fasting  experiment  had  been 
made,  this  would  be  considered  from  every  angle.  But  the  treatment  of 
so  many  fasting  experiments  seems  to  be  best  made  by  a  critical  study  of 
the  computed  heat  values  alone.  The  data  for  all  of  the  longer  fasts  will 
accordingly  be  considered  at  the  same  time.  The  heat  values  have  been 
computed  upon  three  bases:  (1)  the  total  heat-production  per  24  hours, 
computed  from  the  average  of  3  or  4  half-hour  carbon-dioxide  measure¬ 
ments  each  morning;  (2)  the  heat-production  per  500  kg.  of  body-weight 
per  24  hours;  and  (3)  the  heat-production  per  square  meter  of  body-surface 
per  24  hours. 

TOTAL  HEAT-PRODUCTION  PER  24  HOURS 

The  total  daily  heat-production  for  each  day  of  the  fasts  of  5  to  14  days 
is  presented  in  Table  48  for  all  four  animals.  Owing  to  the  fact  that  the 
two  animals  in  each  pair  fasted  during  the  same  periods,  it  was  impossible 
to  make  the  respiration  experiments  with  both  animals  at  the  same  time  of 
day.  Thus,  steer  C  was  usually  studied  first  in  the  respiration  chamber 
and  steer  D  immediately  afterwards,  and  the  same  treatment  was  accorded 
to  steers  E  and  F.  In  Table  48,  therefore,  in  addition  to  the  record  of  the 
number  of  days  that  the  animal  had  been  fasting,  the  number  of  hours  after 
food  when  the  respiration  experiment  was  made  is  also  indicated  for  each 
day.  Thus,  the  respiration  experiments  on  the  first  day  of  fasting  began 
with  all  animals  between  the  twenty-second  and  thirty-second  hour  after 
food  was  withdrawn.  This  time  interval  is  such  that  these  experiments  on 
the  first  day  represent  the  so-called  “standard  metabolism”  experiments 


172 


METABOLISM  OF  THE  FASTING  STEER 


with  steers,  since  in  all  but  one  instance  the  animals  were  standing  during 
the  period  of  measurement.  Standard  metabolism  measurements  were  also 
secured  with  these  animals  from  time  to  time  throughout  the  entire  period 
of  their  study,  and  further  reference  will  be  made  later  to  the  data  reported 
for  the  first  day  of  fasting  in  Table  48,  when  the  standard  metabolism 
experiments  as  a  whole  are  considered.  (See  pp.  228  to  230.) 

The  consideration  of  the  total  heat-production  per  24  hours,  irrespective 
of  the  size  of  the  animal,  its  previous  state  of  nutrition,  and  the  environ¬ 
mental  temperature  to  which  it  has  been  exposed,  precludes  immediately 
any  exact  comparison  of  the  different  fasts  with  each  other,  and  greatest 
stress  must  therefore  be  laid  upon  the  metabolism  during  the  successive 
days  of  any  given  fast.  It  is  first  to  be  observed  that  there  is  immediately 
a  rapid  decrease  in  the  metabolism,  which  continues  as  the  fast  progresses, 
being  roughly  proportional  to  the  length  of  the  fast.  Thus,  in  the  14-day 
fast  in  April  1922,  with  steer  D  the  heat-production  dropped  from  10,500 
calories  on  the  first  day  to  7,800  calories  on  the  fourteenth  day,  a  fall  of 
2,700  calories  per  24  hours.  An  even  greater  fall  was  noticed  in  4  days  in 
the  June  1922  fast  with  this  same  animal,  however,  from  12,700  to  9,300 
calories  on  the  fourth  day,  or  a  drop  of  3,400  calories. 

The  largest  decrease  in  the  heat-production  is  usually  found  between  the 
first  and  the  second  day,  and  this  is  undoubtedly  immediately  incidental  to 
the  withholding  of  food.  This  is  strikingly  shown  in  the  November  1923  fast 
with  steer  D,  when  the  heat-production  fell  from  16,300  calories  on  the  first 
day  to  13,200  calories  on  the  second  day,  a  fall  of  3,100  calories.  After  the 
second  day,  however,  the  decrease  is  for  the  most  part  regular  in  each 
individual  fast,  and  the  total  decrease  is  greater  the  longer  the  fast. 

Although  there  are  differences  in  the  average  level  of  metabolism  in  the 
different  fasts,  it  is  only  in  the  fast  in  March  1924  that  such  a  pronounced 
difference  in  metabolic  level  is  found  as  to  challenge  attention.  Indeed,  the 
metabolism,  particularly  toward  the  end  of  this  fast  with  both  steer  C  and 
steer  D,  is  altogether  different  from  that  at  the  end  of  any  of  the  other  fasts 
of  essentially  the  same  length.  Thus,  the  lowest  value  found  with  steer  C 
prior  to  March  1924  was  7,100  calories  on  the  fourteenth  day  of  the  April 
fast,  and  yet  this  value  is  actually  higher  than  that  measured  on  the  second 
day  of  the  fast  in  March  1924.  With  steer  D  the  lowest  value  found  prior 
to  the  March  fast,  namely,  7,800  calories,  occurred  on  the  tenth,  thirteenth, 
and  fourteenth  days  of  the  April  fast,  and  yet  this  is  larger  than  the  values 
found  on  the  eighth  and  ninth  days  of  the  fast  in  March  1924.  Further 
discussion  of  the  fast  in  March  1924  will  be  entered  into  later,  and  it  need 
only  be  pointed  out  here  that  this  fast  followed  pronouncedly  submain¬ 
tenance  rations.  Incidentally  it  should  also  be  added  that  the  November 
fasts,  both  in  1922  and  1923,  with  both  animals,  followed  pasture  feeding. 
As  has  been  frequently  stated  in  the  text,  steers  E  and  F  were  younger  and 
smaller  than  the  mature  animals,  and  hence  their  seemingly  very  low  heat- 
production  of  between  5,100  and  5,900  calories  is  explained  by  this  fact  as 
well  as  by  the  fact  that  their  fasts  likewise  followed  submaintenance 
feeding. 


Table  48. — Heat-production  per  24  hours  during  fasts  of  5  to  14  days 


METABOLISM  DURING  FASTING 


173 


174 


METABOLISM  OF  THE  FASTING  STEER 


The  pronounced  influence  of  the  previous  state  of  nutrition  upon  the 
fasting  metabolism  is  thus  clearly  indicated,  not  only  by  the  falling  off  in 
the  metabolism  during  each  day  of  the  fast  (because  the  previous  store  of 
food  is  depleted  more  and  more  as  time  goes  on)  but  by  the  general  level 
of  the  fasting  metabolism,  which  is  strikingly  lower  in  the  fasts  following 
submaintenance  feeding.  In  the  case  of  the  two  smaller  animals,  however, 
this  effect  is  not  to  be  observed  from  Table  48  alone,  but  can  only  be  noted 
when  a  comparison  is  made  between  their  fasting  metabolism  at  the  sub¬ 
maintenance  level  and  their  standard  metabolism  following  maintenance 
feeding.  (See  p.  232.) 

Average  figures  can  not  be  drawn  from  the  values  given  in  Table  48  for 
the  total  24-hour  heat-production,  since  all  the  animals  were  changing  in 
weight,  the  previous  states  of  nutrition  were  markedly  different  in  the 
different  fasts,  and  the  environmental  temperature  was  in  some  cases 
changed  unintentionally  and  in  other  cases  it  was  purposely  altered  to  study 
the  influence  of  this  factor  upon  metabolism.  The  general  conclusions  to 
be  drawn,  however,  are  that  there  is  a  rapid  and  persistent  decrease  in  the 
heat-production  of  these  large  ruminants  during  fasting,  and  that  the  previ¬ 
ous  state  of  nutrition,  particularly  when  a  submaintenance  ration  has  been 
given,  has  a  pronounced  influence  upon  the  fasting  metabolism  in  that  the 
metabolism  begins  at  a  much  lower  level  than  in  the  other  cases  and  falls 
to  a  still  lower  level  as  the  fast  progresses.  Finally,  the  same  mature 
animal  within  a  period  of  two  years  may  have  markedly  different  fasting 
levels,  even  if  the  fast  following  submaintenance  feeding  is  excepted. 

HEAT-PRODUCTION  PER  500  KG.  OF  BODY-WEIGHT  PER  24  HOURS 

The  heat-production  of  these  steers  during  the  fasts  of  5  to  14  days  has 
also  been  computed  on  the  basis  of  500  kg.  of  body-weight,®  and  the  values 
are  given  in  Table  49,  in  which  the  days  of  fasting  correspond  exactly  to 
those  reported  in  Table  48.  By  this  method  of  computation  the  differences 
in  the  size  of  the  animal  as  any  one  fast  progresses  and  the  differences  in 
the  size  of  the  same  animal  from  year  to  year  are  taken  into  account,  and 
it  is  permissible  not  only  to  consider  the  data  from  the  standpoint  of  the 
consecutive  days  of  fasting,  but  likewise  to  compare  the  results  obtained  in 
the  various  fasts  and  with  the  different  animals.  The  results  confirm  the 
findings  noted  in  the  analysis  of  the  data  for  the  24-hour  heat-production, 
namely,  that  in  spite  of  the  changes  in  body-weight,  the  metabolism  dis¬ 
tinctly  decreases  during  the  fast,  and  that  usually  the  lowest  values  appear 
at  the  end  of  the  longer  fasts. 

The  lowest  value  found  with  steer  C  outside  of  the  fast  in  March  1924, 
namely,  6,700  calories,  occurred  (as  in  the  case  of  the  total  heat-produc¬ 
tion)  on  the  fourteenth  day  of  fasting.  Although  there  is  some  variability 

°  It  is  particularly  to  be  emphasized  that  in  this  report  the  calculations  of  the  heat-production 
per  500  kg.  of  body-weight  are  derived  by  referring  the  weight  of  the  animal  by  direct  proportion 
to  a  standard  weight  of  500  kg.  and  not  to  the  two-thirds  power  of  the  weight,  which  is  frequently 
done  by  other  writers.  Obviously,  the  heat-production  computed  per  500  kg.  of  body-weight 
has  the  same  significance  as  the  heat-production  per  kilogram  of  body-weight,  so  commonly 
computed  for  man  and  other  animals.  But  it  seems  best  to  refer  the  heat-production  of  these 
large  animals  to  the  approximate  average  weight  of  a  mature  steer,  i.  e.,  500  kg. 


METABOLISM  DURING  FASTING 


175 


in  the  values,  there  is  with  this  animal  a  clear-cut  picture  of  a  continually 
falling  metabolism,  especially  during  the  14-day  fast.  In  the  fast  in  March 
1924,  much  lower  values  are  noted  than  in  any  of  the  other  fasts.  The 
body-weight  was  lower  at  this  time,  but  the  computation  of  the  heat-pro¬ 
duction  per  500  kg.  of  body-weight  eliminates  to  a  certain  extent  any  differ¬ 
ences  due  to  differences  in  body-weight,  and  it  is  thus  evident  that  the  low 
metabolic  level  noted  in  this  March  fast  reflects  the  influence  of  the  preced¬ 
ing  submaintenance  regime. 

In  the  fasts  following  maintenance  feeding,  that  is,  in  the  first  six  fasts 
with  each  of  the  larger  animals,  the  fasting  metabolism  reaches  a  reasonably 
constant  level  on  or  about  the  fourth  or  the  fifth  day,  but  it  can  not  be 
definitely  asserted  that  on  any  certain  day  the  metabolism  had  reached  a 
minimum  point  with  either  animal  in  all  experiments.  This  may  be  in  part 
due  to  the  fact  that  although  the  animals  were  measured  in  the  standing 
position,  the  activity  while  the  animal  was  inside  the  respiration  chamber 
differed  somewhat  from  day  to  day.  It  is  believed,  however,  that  the 
irregularities  in  metabolism  can  by  no  means  be  wholly  explained  by  differ¬ 
ences  in  activity  during  the  respiration  experiment.  The  graphic  records 
show,  it  is  true,  variations  in  the  activity  when  the  animal  was  inside  the 
chamber  and  indicate  that  there  was  a  general  tendency,  although  by  no 
means  uniform,  for  the  animals  to  be  less  active  as  the  fast  progressed.  A 
part  of  the  fall  in  metabolism  shown  in  Table  49  may  therefore  be  due  to 
a  greater  degree  of  repose.  Variability  in  activity  is  one  of  the  great 
stumbling  blocks  in  the  study  of  the  metabolism  of  these  animals,  whose 
activity  can  not  be  controlled.  It  is  a  distinct  argument  in  favor  of  the 
24-hour  experiment,  in  which  the  uniformity  in  stall  activity  would  be 
greater  in  general  than  in  any  chance  three  or  four  consecutive  half-hour 
periods.  Indeed,  at  this  stage  of  our  experimentation  we  were  inclined  to 
believe  that  the  24-hour  period  would  enormously  help  in  the  explanation 
of  these  figures.  But  even  in  24-hour  experiments  irregularity  in  activity 
occurs  persistently,  although  in  general  the  animals  lie  down  a  little  longer 
as  the  fast  progresses.  Since  the  experiments  reported  in  Table  49  com¬ 
prised  three  or  four  consecutive  half-hour  periods  inside  the  respiration 
chamber,  and  the  steer  was  always  forced  to  stand  during  these  short  experi¬ 
ments,  the  chamber  activity  was  for  the  most  part  of  sufficient  relative 
uniformity  so  that  the  differences  could  not  wholly  explain  the  differences 
in  the  metabolism  noted  in  this  table. 

A  second  factor  which  is  known  to  influence  the  metabolism  of  animals 
is  that  of  environmental  temperature.  The  uniformity  in  the  environmental 
temperature  in  these  experiments  was  by  no  means  so  great  as  it  should 
have  been.  This  is  particularly  true  in  the  two  experiments  in  December 
1921,  as  can  be'  seen  by  reference  to  Tables  44  and  45  (pp.  166  and  168). 
Thus,  on  the  two  days  preceding  the  metabolism  measurements,  the  stall 
temperature  for  24  hours  was  low,  5°  C.,  but  the  chamber  temperatures 
during  the  experiment  were  higher,  i.  e.,  from  17°  to  22°  C.  In  the  other  long 
fasts,  however,  there  was  not  such  a  marked  difference  between  the  stall 
temperature  preceding  and  the  chamber  temperature  during  the  experiment. 


Table  49— Heat-production  per  500  kg.  of  body-weight  per  hours  during  fasts  of  5  to  H  days 


176 


METABOLISM  OF  THE  FASTING  STEER 


■>}« 

rH 

336  to 

339 

cal. 

6,700 

7,100 

CO 

T*H 

312  to 

315 

cal. 

6,900 

7,000 

03 

rH 

291  to 

300 

cal. 

7,200 

7,000 

rH 

rH 

267  to 
272 

cal. 

6,900 

7,300 

o 

rH 

241  to 
245 

cal. 

8,200 

7,100 

5,700 

7,400 

6,800 

05 

216  to 
228 

cal. 

7,700 

7,700 

8,200 

6,100 

7,300 

7,000 

6,200 

tc 

00 

•o 

o 

.2 

192  to 
200 

cal. 

7,200 

7,600 

7,700 

6,100 

7,100 

7,100 

6,100 

*>3 

CO 

3 

v-< 

CO 

>> 

3 

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3 

O 

r3 

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168  to 
174 

cal. 

7,600 

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7,100 

6,200 

7,700 

7,600 

7,000 

7,700 

7,000 

o 

o 

Jh 

3 

O 

w 

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CO  ^ 

rH 

cal. 

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7,700 

7,500 

8,000 

7.900 

5.900 

7,900 

7,400 

7,000 

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o  *  o 

o  • 

GO  •  t-T 

<o 

113  to 
128 

cal. 

7,600 

8,100 

7,100 

1 7,400 
7,600 
6,000 

8,000 

7,800 

7,100 

8,700 

7.800 

6.800 

10,600 

89  to 
104 

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rH 

rH 

CO 

65  to 
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11,500 

03 

42  to 
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CO  b-  ©  ©  00  ©  b. 

CO  00  00  ©  ©  ©  b- 

11,700 

O 

O 

00 

o 

rH 

rH 

22  to 
32 

o  o  ©  o  o  o 

.  o  o  o  o  o  © 

~  co  b.  cc  ■<*  oo  jp' <n 

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10,200 

10,000 

8,500 

10,400 

12,000 

8,600 

10,900 

o 

o 

CO 

© 

rH 

- — - 

Steer  and 
dates  of  fasts 

Steer  C: 

Dec.  6  to  13,  1921 _ 

Jan.  4  14,1922... 

Apr.  17  May  1,1922 

June  1  7,1922... 

Nov.  6  16,1922... 

Nov.  4  10,1923... 

Mar.  3  13,  1924 .  .  . 

Steer  D: 

Dec.  6  to  13,  1921 .  .  . 

Jan.  4  14,  1922 . .  . 

Apr.  17  May  1, 1922 

June  1  6,1922... 

Nov.  6  14,1922... 

Nov.  4  9,1923... 

Mar.  3  12,  1924  . . . 

Steer  E: 

Feb.  12  to  17,  1924.  . . 
Steer  F: 

Feb.  12  to  18,  1924. . . . 

H3 

o 

o 


3 

O 

rd 

hh 


»H 

3 

O 

A 

GO 


3 

o 

o 

rQ 

TJ 

3 

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CD 

o 

rC 

+* 

3 

o 

X3 


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3 

£ 

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•H 

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J3 


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0 

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3 


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METABOLISM  DURING  FASTING 


177 


Indeed,  the  changes  in  temperature  from  day  to  day  during  these  fasting 
experiments  were,  for  the  most  part,  very  small,  so  that  any  great  change 
in  the  metabolism  can  not,  save  possibly  in  the  first  experiment,  be  attributed 
to  the  environmental  temperature.  The  average  environmental  temperature 
during  most  of  the  fasts  was  about  20°  C.  In  the  March  fasts  perceptibly 
lower  temperatures  prevailed  and  in  the  June  fasts  perceptibly  higher 
temperatures.  It  is  obvious  that  the  temperature  of  the  chamber  during  an 
experiment  made  in  June  would  be  higher  than  that  during  an  experiment 
made  in  January  of  the  same  year.  Thus,  the  chamber  temperatures  during 
the  fasts  in  June  1922  were  from  26°  to  28°  C.  The  values  for  the  heat- 
production  per  500  kg.  of  body-weight,  however,  are  not  appreciably  lower 
in  the  June  fast  of  steer  C  than  in  the  other  fasts  with  this  animal.  They 
are  somewhat  lower,  for  the  most  part,  than  the  values  in  the  January  fast, 
but  they  are  higher  than  those  in  the  April  fast.  In  the  case  of  steer  D  the 
reverse  is  true,  that  is,  the  June  values  are  actually  higher  than  those  in 
January.  In  fact,  the  highest  values  in  the  series  up  to  that  date  were 
found  in  June  1922. 

In  the  earlier  research  on  undernutrition  in  steers  it  was  noted  that  the 
effect  of  environmental  temperature  seemed  to  be  small  and  was  contrary 
to  the  commonly  accepted  belief  that  the  lower  temperature  is  accompanied 
by  a  higher  metabolism  in  warm-blooded  animals.  Indeed,  certain  of  the 
results  obtained  suggested  strongly  that  the  metabolism  may  be  lower  the 
lower  the  temperature.  The  necessity  for  constancy  in  environmental  tem¬ 
perature  was  therefore  not  stressed  perhaps  as  much  as  it  should  have  been 
in  these  fasting  experiments  of  5  to  14  days.  Subsequently,  however,  a 
special  study  of  the  influence  of  environmental  temperature  was  made  in  a 
series  of  short  fasts  in  1923  (see  pp.  180  to  185)  and  in  a  series  of  4-day 
experiments  with  steers  E  and  F  (see  pp.  200  to  202).  As  no  irritating 
agencies  pestering  the  animals  could  be  accounted  for,  the  difference  in  the 
heat-production  in  this  series  of  fasts  must  be  ascribable  to  true  cell  differ¬ 
ences  in  the  metabolism  of  these  animals  at  different  stages  and  is  not  due 
to  differences  either  in  abnormal  stall  activity  or  in  environmental  tem¬ 
perature.  The  preceding  nutritive  state,  however,  particularly  the  submain¬ 
tenance  level  of  nutrition,  did  have  an  influence. 

Although  it  was  noted  in  Table  48  that  steers  E  and  F  had  a  much  lower 
total  heat-production  on  the  different  days  of  their  fasts  than  did  steers  C 
and  D,  the  calculations  on  the  basis  of  equal  body-weight,  reported  in 
Table  49,  show  that  these  animals  actually  had  a  higher  metabolism  per 
500  kg.  of  body-weight  than  did  the  adult  animals,  especially  after  the  first 
day.  The  metabolism  of  steers  E  and  F  was  higher  even  when  their  fasting 
values  after  submaintenance  feeding  are  compared  with  those  for  steers  C 
and  D  in  the  fasts  after  maintenance  feeding.  Indeed,  on  no  day  was  the 
heat-production  of  steer  F  per  500  kg.  of  body-weight  lower  than  10,300 
calories.  This  evidence  is,  in  all  probability,  to  be  taken  as  an  index  of  the 
greater  activity  of  the  younger  protoplasm,  and  it  is  fully  in  line  with  the 
finding  on  humans  that  the  heat-production  per  kilogram  of  body-weight 
of  the  child  is  always  notably  higher  than  that  of  the  adult. 


Table  50. — Heat-production  per  square  meter  of  body-surface  per  24  hours  during  fasts  of  5  to  1 4  days 


178 


METABOLISM  OF  THE  FASTING  STEER 


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Mar. 

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METABOLISM  =  DURING  FASTING 


179 


HEAT-PRODUCTION  PER  SQUARE  METER  OF  BODY-SURFACE  PER  24  HOURS 

On  pages  153  to  156  the  calculation  of  the  surface  area  of  steers,  based 
upon  various  formulas  suggested  by  recent  writers,  has  been  discussed.  It 
was  there  pointed  out  that  Hogan’s  formula,  in  which  the  five-eighths  power 
of  the  live  weight  in  kilograms  is  multiplied  by  the  constant  0.1081,  probably 
gives  a  reasonably  close  measure  of  the  true  surface  area  in  square  meters. 
It  is  perhaps  unfortunate  that  for  the  comparison  of  the  same  animal  under 
different  conditions  of  flesh  during  fasting,  when  striking  differences  take 
place  within  a  relatively  few  days,  a  better  means  of  determining  the  exact 
surface  area  is  not  available.  In  lieu  of  better  surface-area  measurements 
all  of  the  calculations  of  the  24-hour  heat-production  per  square  meter  of 
body-surface  have  been  made  employing  this  formula.0  These  calculations 
are  summarized  in  Table  50  for  the  same  fasts  and  animals  as  reported  in 
Tables  48  and  49. 

Exactly  as  with  the  total  metabolism  and  the  metabolism  per  500  kg.  of 
body-weight,  there  is  a  pronounced  drop  in  the  heat-production  between  the 
first  and  the  second  days  of  fasting  per  unit  of  body-surface  and  there  is, 
in  general,  a  still  further  drop  as  the  fasts  progress.  The  minimum  value 
in  the  first  six  fasts  again  appears,  in  the  case  of  steer  C,  on  the  fourteenth 
day  of  fasting,  i.  e.,  1,300  calories.  This  value,  however,  is  greater  than 
that  found  on  the  first  day  of  the  fast  in  March  1924,  following  prolonged 
submaintenance  feeding.  The  absolute  minimum  found  with  this  animal  is 
1,110  calories  on  the  second  day  of  the  March  fast.  With  steer  D  the 
lowest  value  found  prior  to  the  fast  in  March  1924  was  1,360  calories  on 
the  tenth  day  of  the  April  fast.  On  the  eighth  and  ninth  days  of  the  fast 
following  submaintenance  feeding  in  March  1924,  values  of  1,230  and  1,260 
calories,  respectively,  were  noted,  the  first  value  being  actually  the  lowest 
in  the  entire  series  with  this  animal. 

In  the  case  of  steer  C,  in  the  fasts  other  than  the  last  one,  uniformity  in 
the  heat-production  per  square  meter  of  body-surface  appears  at  about  the 
fourth  day  of  the  fasts,  but  the  values  for  steer  D  do  not  approach  uni¬ 
formity  until  much  later,  i.  e.,  on  the  seventh  or  eighth  day.  On  the  fifth 
day  in  the  first  six  fasts  of  steer  D  there  is  an  actual  range  in  the  values  of 
from  1,430  to  1,740  calories,  that  is,  22  per  cent.  In  view  of  the  influence  of 
undemutrition  upon  the  fasting  metabolism  of  both  animals  in  March  1924, 
it  is  not  surprising  perhaps  that  these  differences  in  metabolism  are  noted  in 
the  earlier  fasts  of  these  animals,  which  at  times  fasted  after  pasture  feed¬ 
ing  and  at  times  after  stall  feeding  with  supposedly  maintenance  rations. 

°  We  wish  to  call  attention  here  to  the  articles  published  recently  by  Brody  and  Elting  regard¬ 
ing  a  new  method  proposed  by  them  for  measuring  the  surface  area  of  cattle  (Elting,  Journ. 
Agric.  Research,  1926,  33,  p.  269;  Brody  and  Elting,  Univ.  Missouri,  Agric.  Expt.  Sta.,  Bull.  89, 
1926).  These  articles  appeared  after  the  manuscript  of  this  monograph  had  been  sent  to  the 
printer,  and  hence  too  late  for  us  to  make  use  of  their  body-surface  formula  in  our  calculations. 
Brody  and  Elting  propose  the  equation  S  —  0.15  TV0-54  as  expressing  the  relation  between  body- 
weight  and  surface  area,  in  which  S  equals  the  surface  area  in  square  meters  and  W  the  live  weight 
in  kilograms.  At  the  moment  of  writing  we  are  unconvinced  that  this  is  a  real  betterment  of  the 
Hogan  formula,  but  if  the  new  formula  had  been  used  for  our  steers,  the  body-surface  values  for 
steers  C  and  D  would  be  approximately  10  per  cent  lower  than  they  are  by  Hogan’s  formula  and 
those  for  steers  E  and  F  would  be  about  4  per  cent  lower.  Hence,  on  this  basis  the  values  for  the 
heat-production  per  square  meter  of  body-surface  would  be  10  per  cent  and  4  per  cent  higher, 
respectively,  than  we  have  reported  in  this  monograph. 


180 


METABOLISM  OF  THE  FASTING  STEER 


A  comparison  of  the  values  for  the  first  day  of  the  different  fasts,  except¬ 
ing  the  fasts  at  the  submaintenance  level,  shows  no  sign  of  uniformity 
between  the  two  animals  C  and  D.  Steer  D  has  a  distinctly  higher  meta¬ 
bolic  level  than  has  steer  C,  the  single  exception  being  on  the  first  day  of 
the  April  fast,  when  his  heat-production  was  a  little  lower  than  that  of 
steer  C.  On  the  second  day  of  fasting  the  values  for  the  most  part  are 
higher  with  steer  D  than  with  steer  C.  This  is  also  true  in  the  case  of  the 
third  day  of  fasting  and,  indeed,  throughout  essentially  all  of  the  succeeding 
fasting  days,  except  that  in  the  10-day  and  14-day  fasts  the  metabolism  of 
both  animals  is  reasonably  similar  after  the  second  day.  In  the  fast  fol¬ 
lowing  submaintenance  feeding  steer  D  is  upon  a  definitely  higher  metabolic 
level  than  steer  C  until  the  eighth  day  is  reached. 

The  values  for  the  two  smaller  animals,  E  and  F,  on  the  basis  of  equal 
body-surface,  are  for  the  most  part  of  the  same  order  as  those  noted  on  the 
average  with  steers  C  and  D,  but  they  are  notably  higher  than  the  values 
for  steer  C  found  in  his  fast  after  submaintenance  feeding.  The  effect  of 
submaintenance  rations  on  steer  D  was  much  less  pronounced  for  the  first 
7  days  of  fasting  than  it  was  with  steer  C.  In  this  respect  again,  therefore, 
the  evidence  is  that  with  steers  E  and  F,  which  fasted  at  a  submaintenance 
level,  higher  values  for  the  metabolism  per  square  meter  of  body-surface 
per  24  hours  prevail  than  with  one  of  the  two  adult  animals,  steer  C,  at  a 
submaintenance  level.  Indeed,  the  values  for  steers  E  and  F  are  a  little 
higher  than  those  for  steer  D  at  the  submaintenance  level,  a  fact  which 
points  again  to  the  higher  metabolism  of  the  younger  protoplasm. 

Examination  of  all  three  bases  for  comparing  the  heat-production  of  these 
animals  shows  clearly  that  steer  D  is  a  distinctly  different  type  from  steer 
C,  having  a  higher  metabolism  in  all  the  fasts.  This  may  be  partly  explained 
by  the  definitely  greater  stall  activity  of  steer  D,  although  our  experience 
would  lead  us  to  believe  that  this  difference  in  activity  can  not  possibly 
account  entirely  for  the  difference  in  the  metabolism  of  the  two  animals. 
Steers  E  and  F,  younger  and  lighter  in  weight,  have  a  metabolism  of  an 
altogether  different  order  from  that  of  steers  C  and  D.  Their  heat-produc¬ 
tion  per  square  meter  of  body-surface  more  nearly  corresponds  to  that  of 
steer  D  than  that  of  steer  C,  although  it  is  somewhat  higher  than  even  that 
of  the  former.  These  comparisons  bring  out  the  influence  of  individuality 
in  these  animals.  Indeed,  the  word  “temperament”  might  be  ascribed  to 
the  known  restlessness  of  steer  D.  Experiments  in  which  the  nutritive  plane 
is  the  same  or  essentially  the  same  and  in  which  the  animals  are  lying 
quietly  will  be  necessary  to  establish  these  differences  quantitatively  and 
sharply.  That  they  exist  is  highly  probable. 

Heat-production  in  2-day  Fasts  at  a  Maintenance  Level  of  Nutrition 

As  is  clearly  brought  out  in  Tables  48,  49,  and  50  (pp.  173,  176  and  178), 
in  which  the  data  for  the  longer  fasts  are  summarized,  the  most  pronounced 
changes  in  metabolism  due  to  fasting  are  to  be  observed  in  the  first,  second, 
and  third  days.  Hence  it  seemed  desirable  to  supplement  the  longer  fasts 
by  a  series  of  short  fasting  experiments  with  steers  C  and  D,  in  which 
emphasis  would  be  laid  upon  the  earlier  stages  of  the  fast.  Furthermore, 
since  it  was  evident  that  differences  in  nutritive  level  have  a  pronounced 


METABOLISM  DURING  FASTING 


181 

effect  upon  the  fasting  metabolism,  these  experiments  were  planned  to  rule 
out  changes  in  nutritive  level  by  having  the  animals  fast  in  every  case  after 
an  essentially  maintenance  ration.  Opportunity  was  also  taken  to  accentu¬ 
ate  the  influence  of  environmental  temperature,  in  that  many  of  the  experi¬ 
ments  were  made  under  widely  different  temperature  conditions.  It  is 
therefore  impossible  to  compare  directly  the  values  obtained  in  these  short 
fasting  experiments  with  those  obtained  in  the  longer  experiments,  without 
taking  into  consideration  the  differences  in  environmental  temperature  and 
the  fact  that  in  the  series  of  short  fasts  the  animals  were  always  studied  at 
a  maintenance  level  of  nutrition,  but  that  in  the  longer  fasts  they  were 
studied  after  maintenance  and  submaintenance  feeding  and  after  coming 
from  pasture.  Furthermore,  in  comparing  the  first  and  second  days  of 
fasting  in  this  series  of  2-day  fasts,  it  must  be  borne  in  mind  that  not  infre¬ 
quently  the  animals  were  arbitrarily  subjected  to  marked  changes  in 
environmental  temperature  from  one  day  to  the  next. 

Table  51.  Heat-production  of  steers  C  and  D  in  2-day  fasts  at  a  maintenance  level  of 

nutrition 


Steer  and  dates  of 
fasts  (1923) 

Heat-production  per  24  hours 

Total 

Per  500  kg. 

Per  sq.  m. 

Hours  without  food 

25  to  26 

47  to  50 

25  to  26 

47  to  50 

25  to  26 

47  to  50 

Steer  C: 

cal. 

°c. 

cal. 

°C. 

cal. 

cal. 

cal. 

cal. 

Jan.  4  and  5  1 .  .  . 

9,500 

6.3 

9,300 

7.7 

6,900 

6,800 

1,480 

1,460 

Jan.  22  and  23  ...  . 

8,100 

27.9 

9,600 

-1.9 

5,900 

7,000 

1,260 

1,500 

Jan.  29  and  30 ...  . 

11,200 

2.9 

6,800 

24.9 

8,100 

4,900 

1,740 

1,060 

Feb.  6  and  7.  .  .  . 

9,600 

2.6 

10,400 

2.0 

6,900 

7,500 

1,490 

1,610 

Feb.  12  and  13 ...  . 

9,800 

3.9 

9,600 

1.7 

7,100 

7,000 

1,520 

1,500 

Feb.  19  and  20.  .  .  . 

10,700 

2.5 

11,900 

-1.0 

7,800 

8,700 

1,660 

1,860 

Mar.  2  and  3 .  .  .  . 

10,400 

7.3 

8,800 

10.9 

7,500 

6,400 

1,610 

1,370 

Mar.  9  and  10.  .  .  . 

10,100 

4.3 

10,400 

2.0 

7,300 

7,500 

1,570 

1,610 

Mar.  16  and  17.  .  .  . 

10,500 

11.9 

8,900 

24.4 

7,500 

6,400 

1,620 

1,380 

Mar.  23  and  24.  .  .  . 

11,200 

29.2 

9,700 

13.5 

8,200 

7,200 

1,760 

1,530 

Average . 

10,100 

9,500 

7,300 

fi  900 

1  £70 

1  4QH 

Nov.  13,  1924 . 

11,900 

24  4 

7,800 

1  7df) 

Steer  D: 

Jan.  10  and  11  1.  .  . 

11,300 

7.0 

10,200 

7.0 

8,200 

7,400 

1,760 

1,590 

Jan.  18  and  19 ...  . 

11,100 

3.4 

8,300 

28.2 

8,000 

6,000 

1,730 

1,290 

Jan.  26  and  27 ...  . 

11,900 

8.8 

7,600 

28.3 

8,600 

5,500 

1,850 

1,190 

Feb.  2  and  3.  .  .  . 

10,300 

27.9 

9,200 

7.3 

7,600 

6,800 

1,610 

1,450 

Feb.  9  and  10.  .  .  . 

11,300 

8.6 

10,200 

5.7 

8,200 

7,500 

1,760 

1,600 

Feb.  15  and  16.  .  .  . 

12,000 

-1.6 

13,200 

-7.5 

8,600 

9,600 

1,860 

2,050 

Feb.  23  and  24.  .  .  . 

11,400 

3.6 

11,600 

0.2 

8,200 

8,400 

1,770 

1,810 

Mar.  6  and  7.  .  .  . 

11,400 

2.1 

11,600 

0.3 

8,300 

8,400 

1,770 

1,810 

Mar.  14  and  15.  .  .  . 

11,200 

10.5 

10,700 

22.8 

8,100 

7,700 

.1,730 

1,660 

Mar.  21  and  22.  .  .  . 

11,600 

12.6 

10,400 

29.0 

8,400 

7,600 

1,800 

1,620 

Average . 

11,400 

10,300 

8,200 

7,500 

1,760 

1,610 

1  On  Jan.  6  and  12,  with  steers  C  and  D,  respectively,  the  24-hour  heat-production  72  hours 
after  food  was  as  follows:  Steer  C,  8,800  cal.  per  24  hrs.;  6,500  cal.  per  500  kg.;  1,380  cal.  per 
sq.  m.;  steer  D,  8,900  cal.  per  24  hrs.;  6,500  cal.  per  500  kg.;  1,390  cal.  per  sq.  m. 


182 


METABOLISM  OF  THE  FASTING  STEER 


The  values  for  the  computed  heat-production  during  this  series  of  2-day 
fasts  are  summarized  in  Table  51,  being  reported  on  the  three  different  bases 
of  the  total  24-hour  heat-production,  the  heat-production  per  500  kg.  of 
body-weight  per  24  hours,  and  the  heat-production  per  square  meter  of 
body-surface  per  24  hours.  In  addition,  the  average  chamber  temperature 
prevailing  on  each  day  when  the  metabolism  was  measured  is  given  at  the 
right  of  the  values  for  the  total  24-hour  heat-production. 

A  comparison  of  the  values  for  the  total  24-hour  heat-production  is 
justifiable,  since  in  the  short  period  of  3  months  during  which  the  animals 
were  studied,  their  body-weights  did  not  alter  materially,  because  they 
were  always  upon  a  maintenance  level  of  nutrition.  On  the  first  day  of 
fasting,  i.  e.,  25  to  26  hours  after  food,  the  total  heat-production  of  steer  C 
ranged  from  8,100  calories  on  January  22  to  11,200  calories  on  January  29 
and  March  23.  With  steer  D  the  metabolic  level  was  higher,  the  lowest 
value  being  10,300  calories  on  February  2  and  the  highest  being  12,000 
calories  on  February  15.  Contrary  to  our  usual  custom  with  these  animals 
in  the  longer  fasts,  the  2-day  fasts  were  not  made  under  the  same  tempera¬ 
ture  conditions  and  on  the  same  dates  with  each  animal.  Disregarding  for 
the  moment  the  differences  in  environmental  temperature,  we  find  that  the 
average  24-hour  heat-production  of  steer  C  on  the  first  day  is  10,100 
calories  and  of  steer  D  11,400  calories.  Since  these  animals  were  of  almost 
the  same  weight,  the  metabolism  of  steer  D  on  this  basis  is  about  13  per 
cent  higher  than  that  of  steer  C.  The  average  chamber  temperature  during 
the  experiments  with  steer  C  was  9.9°  C.  and  with  steer  D  8.3°  C.,  i.  e., 
somewhat  lower.  Hence  it  might  be  argued  that  the  higher  metabolism 
noted  with  steer  D  might  be  accounted  for  by  the  fact  that  the  average 
environmental  temperature  was  lower  in  his  case.  A  close  examination  of 
the  figures  on  individual  days  shows  that  the  minimum  metabolism  of  steer 
C,  8,100  calories,  occurred  on  January  22,  when  the  environmental  tem¬ 
perature  was  27.9°  C.  On  the  other  hand,  the  maximum  metabolism,  11,200 
calories,  occurred  on  January  29  with  an  environmental  temperature  of  2.9° 
C.,  and  also  on  March  23  with  an  environmental  temperature  of  29.2°  C. 
Hence  with  steer  C  the  effect  of  the  temperature  is  not  clear-cut.  With 
steer  D  the  lowest  value,  10,300  calories,  is  found  on  the  day  with  the 
highest  temperature,  27.9°  C.,  and  the  highest  value,  12,000  calories,  is  found 
on  the  day  with  the  lowest  temperature,  -1.6°  C.  The  difference  between 
these  two  heat  values  represents  an  increase  in  metabolism  of  16.5  per  cent 
with  a  fall  in  temperature  of  approximately  30°.  Although  extremely  high 
temperatures  did  not  prevail  on  any  of  the  other  experimental  days,  an 
examination  of  the  data  for  the  individual  days  other  than  these  two  days 
shows  that  it  is  difficult  to  find  a  distinct  trend  of  low  metabolism  on  days 
with  the  higher  temperatures  and  high  metabolism  on  days  with  the  lower 
temperatures.  Indeed,  the  general  picture  for  the  two  animals  together  does 
not  indicate  a  definite  effect  of  temperature. 

On  the  second  day  of  fasting,  47  to  50  hours  after  the  last  food,  lower 
values  as  a  rule  obtain  with  both  animals,  as  is  to  be  expected  from  the 
analysis  of  the  data  for  the  long  fasts.  With  steer  C  the  lowest  value  on 
the  second  day  is  6,800  calories  with  a  temperature  of  24.9°  C.,  and  the 
highest  value  is  11,900  calories  with  a  temperature  of  -1.0°  C.  Here  there 


METABOLISM  DURING  EASTING 


183 


is  seemingly  clear  evidence  of  an  effect  of  environmental  temperature,  and 
yet  an  examination  of  the  values  on  other  dates  shows  that  although  in 
general  the  metabolism  is  higher  the  lower  the  temperature,  this  is  by  no 
means  invariably  the  case.  With  steer  D  the  lowest  metabolism  on  the 
second  day  is  7,600  calories  on  January  27  with  a  temperature  of  28.3°  C., 
and  the  highest  is  13,200  calories  on  February  16  with  a  temperature  of 
—7.5°  C.  Here  again  a  higher  metabolism  is  noted  with  a  low  temperature, 
and  yet  with  the  high  temperature  on  March  22  the  metabolism  is  10,400 
calories  as  compared  with  7,600  calories  on  January  27,  when  the  tempera¬ 
ture  was  also  high. 

The  influence  of  temperature  may  furthermore  be  specially  studied  by 
comparing  the  instances  where  great  differences  in  temperature  were  arti¬ 
ficially  produced  on  two  consecutive  days.  Thus,  with  steer  C  on  January 
22  the  temperature  was  held  at  27.9°  C.,  and  the  next  day  at  -1.9°  C.  In 
spite  of  the  fact  that  in  the  experiment  made  at  —1.9°  C.  steer  C  had  been 
fasting  for  2  days,  the  24-hour  heat-production  was  9,600  calories  as  com¬ 
pared  with  8,100  calories  on  the  first  day  at  27.9°  C.  In  the  next  fast,  on 
January  29  and  30,  the  increase  in  temperature  on  the  second  day  has 
accentuated  the  normal  fall  in  metabolism  on  the  second  day  of  fasting, 
since  on  the  first  day  the  metabolism  was  11,200  calories  at  2.9°  C.  and  on 
the  second  day  at  24.9°  C.  it  was  but  a  little  over  one-half  as  great,  i.  e., 
6,800  calories.  On  February  19  and  20  the  metabolism  was  a  little  higher 
on  the  second  day  than  on  the  first,  but  apparently  with  the  low  tempera¬ 
tures,  such  as  prevailed  on  March  9  and  10,  the  influence  of  fasting  is  less 
pronounced,  for  with  essentially  the  same  temperature  on  both  days  the 
metabolism  is  the  same.  On  January  18  and  19,  with  steer  D  the  increase 
in  temperature  on  the  second  day  accentuated  the  normal  loss  in  heat- 
production  as  a  result  of  fasting.  This  is  also  true  on  January  26  and  27. 
On  February  15  and  16  a  drop  in  temperature  of  6°  has  seemingly  raised 
the  metabolism  on  the  second  day  actually  above  that  on  the  first,  and  yet 
on  March  15  a  rise  of  12°  in  the  temperature  hardly  influenced  the  heat- 
production.  On  November  13,  1924,  at  a  temperature  of  24.4°  C.,  steer  C 
produced  11,900  calories  on  the  second  day,  a  value  which  is  identical  with 
the  highest  value  on  the  second  day  noted  on  February  20,  1923,  and  yet 
on  November  13,  1924,  the  environmental  temperature  was  24.4°  C.  while 
on  February  20, 1923,  it  was  —1.0°  C. 

An  examination  of  the  records  of  stall  temperature  during  the  24  hours 
immediately  preceding  the  metabolism  measurements  during  these  short 
fasts  indicates  that  in  nearly  every  instance  the  stall  temperature  was 
essentially  the  same  as  the  chamber  temperature  during  the  respiration 
experiment.  There  were  a  few  cases,  however,  when  the  stall  temperature 
was  markedly  different  from  the  chamber  temperature.  Thus,  on  March  17, 
1923,  steer  C  was  placed  in  the  respiration  chamber  at  a  temperature  of 
24.4°  C.,  after  having  been  for  24  hours  previous  in  his  stall  at  a  tempera¬ 
ture  of  8°  C.  On  March  24,  1923,  the  chamber  temperature  was  13.5°  C. 
as  compared  with  a  stall  temperature  of  22°  C.  during  the  preceding  24 
hours.  Similarly,  in  the  case  of  steer  D  on  March  15,  1923,  the  stall  tem¬ 
perature  had  been  5°  C.  and  the  chamber  temperature  was  22.8°  C.,  and  on 
March  21,  1923,  the  stall  temperature  had  been  24°  C.  and  the  chamber 


184 


METABOLISM  OF  THE  FASTING  STEER 


temperature  was  12.6°  C.  It  is  possible  that  a  sudden  marked  change  in 
temperature  may  cause  a  temporary  disturbance  in  the  animal’s  heat-loss 
and  heat-production.  Experiments  made  under  such  conditions  do  not, 
therefore,  lend  themselves  to  the  study  of  the  effect  of  a  high  or  low  environ¬ 
mental  temperature  upon  metabolism  so  well  as  do  experiments  made  under 
conditions  when  the  animal  has  been  living  for  one  or  two  weeks  at  least  at 
the  same  environmental  temperature  in  the  stall  as  is  to  prevail  during  the 
respiration  experiment.  It  was  therefore  planned  to  include  in  our  research 
a  series  of  experiments  made  under  such  conditions,  to  study  the  effect  of 
wide  differences  in  temperature.  These  experiments  will  be  considered  later 
(see  pp.  200  to  202). 

On  January  6  and  12,  respectively,  the  metabolism  of  steers  C  and  D  was 
studied  72  hours  after  food  and  was  found  to  have  fallen  perceptibly  in  both 
cases,  with  no  very  pronounced  changes  in  the  environmental  temperature. 
This  finding  is  in  line  with  the  picture  shown  in  the  longer  fasts. 

It  is  hardly  feasible  to  compare  the  metabolism  on  the  first  and  second 
days  of  the  short  fasts  (see  Table  51,  p.  181),  with  the  metabolism  on  the 
same  days  in  the  longer  fasts  (see  Table  48,  p.  173),  for  there  were  differ¬ 
ences  in  body-weights  in  the  longer  experiments,  and  no  averaging  of  the 
data  in  Table  48  is  justifiable  on  account  of  the  different  metabolic  levels 
at  which  the  longer  fasts  began. 

A  further  factor  which  prevents  a  comparison  of  the  short  fasts  with  the 
longer  fasts  is  the  influence  upon  metabolism  of  the  marked  temperature 
differences  designedly  employed  in  the  series  of  short  fasts.  It  is  only  when 
the  metabolism  is  computed  upon  the  basis  of  equal  size,  that  is,  per  500 
kg.  of  body-weight  or  per  square  meter  of  body-surface,  that  any  compari¬ 
sons  are  justifiable.  But  even  on  this  basis  one  must  carefully  avoid  com¬ 
parison  with  the  experiment  in  March  1924,  which  was  made  at  a  submain¬ 
tenance  level,  and  one  must  also  bear  in  mind  the  influence  of  sudden 
changes  in  environmental  temperature. 

The  picture  of  the  24-hour  heat-production  per  500  kg.  of  body-weight 
during  the  2-day  fasts  in  1923  is  essentially  the  same  as  that  of  the  total 
heat-production,  for  the  body-weights  of  the  two  animals  were  essentially 
alike  and  changed  but  little  throughout  the  series  of  fasts.  Much  the  same 
picture  is  also  shown  by  the  heat-production  per  square  meter  of  body- 
surface.  An  extraordinarily  low  value  of  1,060  calories  per  square  meter 
of  body-surface  was  noted  with  steer  C  on  January  30  with  an  environ¬ 
mental  temperature  of  24.9°  C.  and  a  low  value  of  1,190  calories  was  noted 
with  steer  D  on  January  27  with  an  environmental  temperature  of  28.3°  C. 
These  two  figures  more  nearly  approximate  the  conventional  1,000  calories 
per  square  meter  of  body-surface,  which  many  physiologists  believe  repre¬ 
sents  the  general  heat-production  of  warm-blooded  animals.  Too  little  is 
as  yet  known,  however,  with  regard  to  the  influence  of  environmental  tem¬ 
perature  upon  animals  to  make  any  generalizations.  It  is  hardly  conceiv¬ 
able  that  the  normal  environmental  temperature  of  a  ruminant  should  be 
25°  to  28°  C.  or  higher,  and  yet  this  temperature  more  nearly  approximates 
the  “private  climate”0  of  the  clothed  human  than  does  the  ordinary  stall 

°  Dorno,  C.,  Medical  climatology  and  high-altitude  climate,  Vieweg  and  Son,  Brunswick,  1924, 
p.  58. 


METABOLISM  DURING  FASTING 


185 


temperature  or,  indeed,  the  conventional  20°  C.  maintained  in  the  ordinary 
experiments  in  the  respiration  chamber  or  respiration  calorimeter.  If  these 
low  values  had  been  repeatedly  found,  much  more  credence  could  be  given 
to  their  significance.  They  do  not  appear  in  the  long  fasts,  where  one 
would  expect,  if  anywhere,  to  find  a  very  low  heat-production  per  square 
meter  of  body-surface.  Indeed,  the  lowest  values  noted  in  the  long  fasts, 
other  than  m  the  fasts  following  submaintenance  feeding,  were  1,300  calories 
per  square  meter  of  body-surface  with  steer  C  and  1,360  calories  with 
steer  D.  All  of  these  measurements,  however,  were  made  with  the  animal 
standing,  and  it  may  be  argued  that  the  difference  above  the  conventional 
1,000  calories  per  square  meter  of  body-surface  may  be  in  large  part 
explained  by  the  extra  effort  of  standing.  Further  discussion  of  this  point 
will  be  deferred  until  later  (see  p.  218).  It  is  sufficient  to  state  at  this 
point  that  it  is  not  believed  that  the  difference  in  metabolism  in  the  two 
positions  can  possibly  explain  the  values  noted  for  the  heat-production  per 
square  meter  of  body-surface. 

Measurement  op  Fasting  Metabolism  in  Three  Consecutive  24-hour  Periods 

The  basic  principle  of  studying  the  metabolism  of  ruminants  in  short 
periods  has  frequently  been  challenged.  The  history  of  the  change  from 
long  to  short  periods  in  the  study  of  the  metabolism  of  ruminants  is  not 
unlike  that  with  other  animals  and  humans.  Practically  all  of  the  work  on 
humans  by  Atwater  and  his  associates  with  the  respiration  calorimeter  at 
Wesleyan  University,  Middletown,  Connecticut,  was  based  upon  24-hour 
periods.  Armsby,  building  a  calorimeter  on  the  model  of  the  Wesleyan  Uni¬ 
versity  apparatus,  likewise  used  the  24-hour  period.  With  humans  it  was 
soon  seen  that  much  valuable  information  could  be  obtained  at  far  less 
expense  by  making  metabolism  measurements  in  shorter  periods,  from 
which  the  probable  24-hour  metabolism  could  be  computed.  The  24-hour 
period,  which  includes  the  profound  influence  upon  metabolism  of  variations 
m  muscular  activity,  body  position,  and  digestion  of  food,  is  a  near  com¬ 
posite  of  the  daily  life,  but  a  period  of  this  length  gives  no  true  knowledge 
with  regard  to  the  basal  metabolism,  the  increment  due  to  change  in 
position,  or  the  increment  due  to  food.  All  of  these  features  must  be 
determined  in  short  periods. 

It  was  recognized  at  the  outset  that  it  would  be  impossible  to  attempt  to 
prescribe  any  definite,  predetermined  degree  of  muscular  activity  or  repose 
m  the  case  of  these  non-cooperating  ruminants.  The  peak  effect  of  the 
digestion  of  food  was  avoided  in  the  short  periods  of  measurement  by 
studying  the  animal  24  hours  after  the  ingestion  of  food,  and  variation  in 
body  position  was  avoided  by  making  it  impossible  for  the  animal  to  lie 
down,  although  the  activity  during  standing  was  not  controllable  and  there¬ 
fore  variable.  The  animals  were  prevented  from  lying  down  primarily 
because  it  was  assumed  that  there  is  a  difference  of  from  about  10  to  30  per 
cent  in  the  metabolism  of  an  animal  in  the  standing  as  compared  to  the 
lying  position.  It  was  impossible  to  make  the  animal  lie  down  and  remain 
lying  the  entire  time,  but  he  could  be  kept  standing  up.  Under  these  con¬ 
ditions  the  so-called  “standard  metabolism”  measurements  were  made.  Are 
measurements  of  the  metabolism  under  such  conditions  suitable  for  pre- 


186  METABOLISM  OF  THE  FASTING  STEER 


Table  52. — Metabolism  of  fasting  steers,  measured  in  three  consecutive  24-hour  periods 


Steer, 

date, 

live  weight,  and 
average  chamber 
temperature 
(1924) 

Hours 

standing 

Hours 

lying 

Hours 
without 
food  to 
begin¬ 
ning  of 
experi¬ 
ment 

Carbon 
dioxide 
pro¬ 
duced 
in  8 
hours 

Respira¬ 

tory 

quo¬ 

tient 

Heat  pro 

Total 

duced  per 

Per 

500  kg. 

24  hours 

Per 
sq.  m. 

Steer  F: 

gm. 

cal. 

cal. 

cal. 

Apr.  1 . 

4  ^ 

3^ 

24 

881.6 

0.84 

7,800 

13,200 

2,060 

295.2  kg... 

3  X 

32 

844.8 

(.80) 

7,700 

13,000 

2,040 

11.6°  C..  . 

iy2 

ey 

40 

744.0 

(-78) 

7,000 

11,900 

1,850 

Average  .... 

9y 

14H 

823.5 

7,500 

12,700 

1,980 

Apr.  2 . 

4 

4 

48 

750.4 

(.76) 

7,200 

12,700 

1,960 

(283 . 0  kg.) 

6 

2 

56 

737.6 

(.74) 

7,200 

12,700 

1,960 

16.3°  C.. . 

2 

6 

64 

700.8 

(.73) 

6,900 

12,200 

1,880 

Average. . . 

12 

12 

729.6 

7,100 

12,500 

1,930 

Apr.  3 . 

5 

3 

72 

705.6 

(.71) 

7,100 

13,100 

1,970 

*271.8  kg... 

5 

3 

80 

699.2 

(.71) 

7,100 

13,100 

1,970 

18.0°  C..  . 

2 

6 

88 

689.6 

.71 

7,000 

12,900 

1,940 

Average . 

12 

12 

698.1 

7,100 

13,000 

1,960 

Steer  E  . 

Apr.  9 .  .  .  . 

6 

2 

24 

886.3 

.82 

8,000 

14,300 

2,190 

280.0  kg... 

6 

2 

32 

786.9 

(.80) 

7,200 

12,900 

1,970 

17.7°  C.. . 

6 

2 

40 

810.2 

(.78) 

7,600 

13,600 

2,080 

Average . 

18 

6 

827.8 

7,600 

13,600 

2,080 

Apr.  10 . 

7 

1 

48 

728.8 

(.76) 

7,000 

13,000 

1,960 

(270.0  kg.) 

3 

5 

56 

728.1 

(.74) 

7,100 

13,100 

1,980 

17  4°  C 

3 

5 

64 

736.5 

(.73) 

7,300 

13,500 

2,040 

Average . 

13 

11 

731.1 

7,100 

13,200 

1,990 

Apr.  11 . 

5 

3 

72 

763.7 

(.71) 

7,700 

14,800 

2,200 

260.8  kg... 

8 

0 

85 

1 713.6 

.71 

1 7,200 

113,800 

1 2 , 060 

18.0°  C... . 

3 

5 

88 

659.7 

.71 

6,700 

12,800 

1,890 

Average. . . 

16 

8 

712.3 

7,200 

13,800 

2,050 

Steer  C: 

Apr.  23 . 

5 

3 

24 

1,317.2 

.89 

11,100 

8,300 

1,760 

669.6  kg... 

3 

5 

32 

1,171.0 

(.80) 

10,700 

8,000 

1,700 

19.6°  C... . 

3 

5 

40 

1,167.1 

(.78) 

10,900 

8,100 

1,730 

Average . 

11 

13 

1,218.4 

10,900 

8,100 

1,730 

Apr.  24 . 

5 

3 

48 

1,145.5 

(.76) 

10,900 

8,500 

1,770 

(644.8  kg.) 

4 

4 

56 

1,035.9 

(.74) 

10,100 

7,800 

1,640 

20.7°  C... . 

4 

4 

64 

991.6 

(.73) 

9,800 

7,600 

1,590 

Average . 

13 

11 

1,057.7 

10,300 

8,000 

1,670 

Apr.  25 . 

6 

2 

72 

997.9 

(.71) 

10,100 

8,100 

1,680 

620.0  kg... 

4 

4 

80 

963.5 

(.71) 

9,700 

7,800 

1,610 

17.4°  C.... 

4 

4 

88 

944.6 

.71 

9,500 

7,700 

1,580 

Average . 

14 

10 

968.7 

9,800 

7,900 

1,620 

1  Based  on  a  period  of  2  hours  and  58  minutes,  because  electric  power  went  off  at  start  of  8-hour 


period. 


METABOLISM  DURING  FASTING  187 


Table  52.  Metabolism  of  fasting  steers,  measured  in  three  consecutive  24-hour  periods — Cont. 


Steer, 

date, 

live  weight,  and 
average  chamber 
temperature 
(1924) 

Hours 

standing 

Hours 

lying 

Hours 
without 
food  to 
begin¬ 
ning  of 
experi¬ 
ment 

Carbon 
dioxide 
pro¬ 
duced 
in  8 
hours 

Respira¬ 

tory 

quo¬ 

tient 

Heat  produced  per  24  hours 

Total 

Per 

500  kg. 

Per 
sq.  m. 

Steer  D: 

am. 

cal. 

cal. 

cal. 

May  14 . 

8 

0 

24 

1,499.7 

0.92 

12,300 

9,300 

1,960 

664.6  kg.. . 

6 

2 

32 

1,437.0 

(.80) 

13,200 

9,900 

2,100 

24.4°  C... . 

5 

3 

40 

1,246.1 

(.78) 

11,700 

8,800 

1,860 

Average . 

19 

5 

1,394.3 

12,400 

9,300 

1,970 

May  15 . 

5 

3 

48 

1,264.9 

(.76) 

12,100 

9,400 

1,970 

(643.0  kg.) 

4 

4 

56 

1,256.0 

(.74) 

12,300 

9,600 

2,000 

24.4°  C... . 

3K 

4M 

64 

1,133.6 

(.73) 

11,200 

8,700 

1,820 

Average . 

12  y2 

HH 

1,218.2 

11,900 

9,200 

1,930 

May  16 

5 

3 

72 

1,170.8 

(.72) 

11,700 

9,400 

1,940 

621.4  kg.. . 

4 

4 

80 

1,129.8 

(.72) 

11,300 

9,100 

1,880 

22.4°  C... . 

4 

4 

88 

1,128.6 

.72 

11,300 

9,100 

1,880 

Average . 

13 

11 

1,143.1 

11,400 

9,200 

1,900 

dieting  the  24-hour  metabolism  of  a  stall-confined  animal?  Are  they  suit¬ 
able  for  computing  the  basal  or  the  lowest  metabolism  of  an  animal,  or  do 
they  have  the  same  error  involved  in  the  24-hour  experiments  with  men, 
in  that  the  variable  activity  makes  computations  of  any  fundamental 
values  highly  unsatisfactory? 

In  the  discussion  of  the  2-day  fasts  (see  p.  184)  it  was  pointed  out  that 
the  24-hour  heat-production  per  square  meter  of  body-surface  was  invari¬ 
ably  higher  and  generally  much  higher  than  the  conventional  1,000  calories 
commonly  ascribed  to  all  warm-blooded  animals.  It  was  suggested  that 
this  might  be  due  to  the  environmental  temperature  and  to  the  fact  that 
our  animals  were  standing  instead  of  lying.  To  rule  out  the  error  in  the 
computation  of  the  24-hour  metabolism  from  a  2-hour  period  of  measure¬ 
ment,  it  was  decided  to  make  some  experiments  with  the  animal  fasting 
inside  the  respiration  chamber,  to  begin  the  experiment  24  hours  after  the 
last  food  was  eaten,  and  to  continue  it  for  three  consecutive  24-hour  periods. 
The  animal  was  to  be  allowed  to  lie  or  stand  at  will.  No  food  was  given, 
but  drinking-water  was  supplied.  The  length  of  time  that  the  animal  stood 
and  lay  down  was  carefully  recorded.  The  usual  kymograph  records  of 
the  activity  of  the  animal  in  the  chamber  stall  were  kept,  although  the 
records  were  at  times  vitiated  by  defects  in  the  tambour,  so  that  they  do 
not  serve  the  purpose  of  exactly  quantitating  the  degree  of  activity  in  all 
cases.  The  temperature  element  was  ruled  out,  in  that  essentially  the  same 
temperature  was  maintained  on  each  day  in  any  given  experiment  with  an 
animal.  In  the  different  experiments  with  the  different  animals  there  were, 
however,  small  differences  in  temperature  (see  p.  189).  Four  such  experi¬ 
ments  were  made  in  April  and  May  1924,  one  with  each  of  the  four  steers. 
The  results  are  tabulated  in  Table  52. 


188 


METABOLISM  OF  THE  FASTING  STEER 


Prior  to  these  experiments,  a  24-hour  respiration  experiment  had  been 
made  with  steer  C,  primarily  to  test  the  feasibility  of  making  24-hour 
experiments  with  this  apparatus  and  with  our  undermanned  staff.  A 
technique  was  finally  devised  whereby  24-hour  experiments  could  be  carried 
out  and  the  carbon-dioxide  production  collected  in  8-hour  periods.  It  was 
impossible  to  secure  duplicate  aliquots  of  the  chamber  air  during  these 
8-hour  periods,  and  each  carbon-dioxide  measurement  therefore  depends 
upon  the  increment  in  weight  of  one  set  of  absorbing  bottles,  which  were  * 
connected  with  and  disconnected  from  the  ventilating  system  at  the  begin¬ 
ning  and  end  of  each  period.  Utmost  precautions  were  taken  to  check  not 
only  the  actual  weights  on  the  pan,  but  to  check  the  oscillation  of  the 
balance  and  to  check  the  absence  of  gaskets  used  to  connect  the  bottles 
with  each  other.  Every  precaution  was  therefore  taken  to  avoid  errors  in 
weight.  But  the  determinations  were  not  made  in  duplicate,  and  hence  are 
remotely  liable  to  possible  error.  From  a  subsequent  examination  of  the 
data,  however,  we  feel  confident  that  rarely  can  the  presence  of  an  error  be 
suspected.  As  pointed  out  in  an  earlier  discussion  of  the  technique  used 
with  this  apparatus,0  after  several  months’  experience  with  a  double  system 
of  absorbers  in  which  duplicate  quantities  of  air  were  collected,  the  agree¬ 
ment  between  duplicate  samples  was  almost  without  exception  of  the  highest 
order,  particularly  after  the  first  few  months  of  experimentation.  This 
agreement  in  duplication  was  so  exact  that  we  felt  justified  in  reducing  the 
number  of  absorbing  trains  to  one  for  each  period,  thereby  making  it  pos¬ 
sible  for  our  small  staff  to  carry  out  these  long  experiments.  Originally  it 
was  planned  to  use  the  apparatus  only  for  a  series  of  perhaps  four  half-hour 
periods,  in  which  to  a  certain  extent  each  half-hour  period  would  be  a  check 
upon  the  other  periods.  Although  duplicate  measurements  were  not  pos¬ 
sible  in  the  8-hour  periods,  each  subsequent  8-hour  period  may  be  looked 
upon  as  a  check  upon  the  one  prior  to  or  following  it,  particularly  when  the 
animal  is  fasting.  In  the  transitional  period  from  feeding  to  fasting  such 
can  not,  of  course,  be  the  case.  On  the  whole,  however,  the  possibility  of 
error  is  remote,  but  we  feel  it  our  duty  to  call  attention  to  it. 

The  carbon-dioxide  measurements  reported  in  Table  52  were  all  made  in 
8-hour  periods,  save  in  the  second  period  on  April  11  with  steer  E,  when, 
owing  to  an  unavoidable  interruption  in  electric  power,  it  was  possible  to 
secure  a  measurement  only  for  2  hours  and  58  minutes.  In  this  case,  how¬ 
ever,  an  analysis  of  the  carbon-dioxide  residual  in  the  chamber  was  made 
at  the  beginning  and  end  of  the  period  so  as  to  make  it  possible  to  compute 
the  8-hour  carbon-dioxide  production  from  the  measurement  for  2  hours 
and  58  minutes.  Although  the  discussion  of  these  experiments  will  be  based 
for  the  greater  part  upon  the  computations  on  the  24-hour  basis,  the  carbon- 
dioxide  measurements  are  reported  on  the  8-hour  basis  because  they  were 
actually  determined  in  this  length  of  time  and  will  serve  to  show  the  trend 
of  the  fasting  metabolism,  particularly  on  the  first  day. 

The  respiratory  quotient  was  determined  at  the  beginning  of  the  first 
8-hour  period  of  the  three  days  and  again  at  the  end  of  the  fast.  For  the 
computation  of  the  heat  values  in  the  intervening  periods  when  the  respira- 

*  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  67. 


METABOLISM  DURING  FASTING 


189 


tory  quotient  was  not  actually  determined,  assumptions  have  been  made, 
based  upon  an  extensive  series  of  actual  determinations  with  animals  under 
conditions  closely  approximating  those  obtaining  in  these  experiments.  The 
rate  of  fall  in  the  respiratory  quotient  is  obviously  most  rapid  on  the  first 
day,  but  on  the  third  day  the  quotient  was  found  to  be  almost  uniformly  a 
fasting  quotient  of  0.71  or  0.72.  It  would  have  been  preferable  to  have 
determined  the  respiratory  quotient  in  each  period,  but  this  was  impossible 
with  the  small  staff  at  our  disposal.  It  is  hardly  probable,  however,  that 
any  serious  error  has  been  introduced  by  the  interpolated  quotients  given  in 

The  heat-production  during  each  8-hour  period  is  recorded  on  the  usual 
three  bases  of  the  total  24-hour  heat-production,  and  the  24-hour  heat- 
production  per  500  kg.  of  body-weight  and  per  square  meter  of  body- 
surface.  Although  it  would  seem  as  if  this  calculation  should  be  made  upon 
the  8-hour  basis,  for  purposes  of  comparison  with  the  computed  metabolism 
in  other  experiments  it  seems  best  to  make  the  calculations  on  the  24-hour 
basis.  The  average  heat-production  for  the  day,  however,  has  the  greatest 
value. 

It  is  unfortunate  that  the  chamber  temperature  could  not  have  been  the 
same  in  the  case  of  all  four  animals.  On  the  first  day  of  the  first  experi¬ 
ment,  unexpectedly  cold  weather  and  a  fall  of  snow  made  such  heavy 
demands  upon  our  heating  system  that  the  temperature  could  not  be  main¬ 
tained  above  an  average  value  of  11.6°  C.  On  the  other  hand,  in  the 
middle  of  May,  the  warm  environmental  temperature  made  it  impossible 
to  carry  out  the  experiment  with  steer  D  at  a  temperature  below  about 
24°  C.,  which  prevailed  for  the  3  days. 

For  several  weeks  prior  to  these  3-day  experiments  the  steers  had  been 
receiving  supposedly  maintenance  rations,  but  they  had  probably  in  no  case 
sufficiently  recovered  from  the  preceding  period  of  submaintenance  feeding, 
followed  by  fasting,  and  the  nutritive  state  was  undoubtedly  somewhat 
below  par.  Steers  C  and  D  had  fasted  for  10  and  9  days,  respectively,  fol¬ 
lowing  10  weeks  on  a  submaintenance  ration,  and  then  each  was  given  9 
kg.  of  hay  daily,  a  supposedly  maintenance  ration.  Steer  C  was  subjected 
to  a  4-day  fast  beginning  on  April  22,  after  having  been  only  39  days  on 
the  ration  of  9  kg.  of  hay  to  recover  from  the  stringent  ration  reduction  and 
the  10-day  fast.  Steer  D  did  not  commence  his  4-day  fast  until  three  weeks 
later,  so  that  he  had  a  better  opportunity  for  complete  recuperation.  Steers 
E  and  F  had  likewise  been  subjected  to  a  long  period  of  submaintenance 
feeding  lasting  8  weeks,  followed  by  a  5-day  and  a  6-day  fast,  respectively, 
and  then  they  were  given  a  maintenance  ration  of  5  kg.  of  hay  and  0.91  kg. 
of  meal  daily  for  4  or  5  weeks  prior  to  the  continuous  3-day  metabolism 
measurements.  At  this  time  they  were  distinctly  underweight,  for  although 
they  weighed  the  same  as  they  had  6  months  before,  when  they  were  first 
received  at  the  laboratory,  they  should  normally  have  weighed  much  more, 
since  they  were  young,  growing  animals.  All  four  steers  were  therefore 
under-nourished  rather  than  over-nourished  at  the  time  of  these  experi¬ 
ments,  and  from  the  well-known  influence  of  undernutrition  upon  metabo¬ 
lism,  one  could  expect  that  these  animals  would  have  a  low  rather  than  a 


190 


METABOLISM  OF  THE  FASTING  STEER 


high  metabolism,  and  hence  that  the  values  found  with  them  would  be 
minimum  rather  than  maximum.  It  will  be  seen  later  (see  p.  191)  that 
the  metabolism  per  square  meter  of  body-surface  was  as  high  in  these 
experiments  as  in  the  earlier  fasts  at  the  maintenance  level  of  nutrition,  and 
we  have  reason  to  believe  that  if  the  level  of  nutrition  at  the  time  of  these 
experiments  in  1924  had  been  a  full  maintenance  one,  the  measured  metabo¬ 
lism  would  have  been  even  higher  than  it  was  found  to  be. 

All  four  experiments  began  and  ended  between  7h  30m  a.  m  and  8  a.  m. 
Each  animal  was  inside  the  respiration  chamber  for  72  consecutive  hours, 
the  first  period  beginning  24  hours  after  the  last  ingestion  of  food.  (See 
Table  11,  p.  53,  for  record  of  last  feed  prior  to  the  experiment.)  The 
body-weights  were  determined  at  the  beginning  and  end  of  each  experiment, 
but  the  weight  for  the  second  day  had  to  be  assumed,  based  upon  the  aver¬ 
age  of  the  initial  and  final  weights.  Steer  C  drank  no  water  during  his 
experiment.  Steer  D  drank  14  kg.  The  amount  taken  by  steers  E  and  F 
is  unknown. 

An  examination  of  the  data  in  Table  52  for  the  hours  spent  in  standing 
and  lying  indicates  that  in  the  first  experiment  steer  F  spent  in  general 
about  half  the  day  standing  and  half  the  day  lying,  although  the  lying 
period  on  the  first  day  was  a  little  longer  than  the  standing  period.  Some¬ 
times  the  lying  period  in  any  8-hour  period  might  be  extended  to  6  hours 
or  reduced  to  1  or  2  hours,  or  the  animal  might  stand  the  entire  8  hours.  In 
the  fasts  of  5  to  14  days  the  animals  were  inclined  to  spend  from  14  to  15 
hours  each  day  lying  down.  In  these  continuous  3-day  experiments,  on  the 
contrary,  the  animals  generally  stood  each  day  at  least  50  per  cent  of  the 
time,  for  only  on  the  first  day  of  the  fasts  with  steer  F  and  with  steer  C 
was  the  time  spent  in  lying  greater  than  the  time  spent  in  standing.  The 
kymograph  records  of  activity  are  complicated  by  the  fact  that  occasionally 
the  apparatus  was  defective.  From  an  inspection  of  these  records  for  the 
3-day  experiments  in  1924,  it  would  appear  that  steer  D  was  somewhat 
more  restless  than  steer  C,  and  steer  E  was  more  restless  than  steer  F.  A 
general  inspection  of  the  kymograph  records  for  all  the  experiments  through¬ 
out  the  whole  period  of  research  also  indicates  that  steer  D  was  more  rest¬ 
less  than  steer  C,  but  that  there  was  little  difference  between  the  activities 
of  steers  C,  E,  and  F.  It  is  believed  that  steer  D  was,  on  the  whole,  a  little 
more  restive  than  any  of  the  other  three  animals,  although  in  general  all 
of  the  animals  were  remarkably  quiet  inside  the  chamber.  Our  experience 
with  our  first  group  of  12  steers  in  the  research  on  undernutrition  showed 
the  degree  of  restlessness  which  can  be  expected  inside  the  respiration  cham¬ 
ber  from  an  untrained  animal.  Judged  on  the  basis  of  this  experience,  steers 
C,  D,  E,  and  F  were  highly  trained  and  remained  extraordinarily  quiet  even 
for  stall-confined  animals. 

The  carbon-dioxide  production  usually  falls  off  markedly  in  the  succes¬ 
sive  periods  on  the  first  day,  and  the  decrease  continues  on  the  next  two 
days.  The  minimum  value  in  every  case  occurs  in  the  last  period  of  the 
experiment,  indicating  that  the  lowest  carbon-dioxide  production  had  not 
been  obtained  at  that  time,  a  finding  fully  in  conformity  with  the  persistent 
decrease  in  metabolism  noted  in  the  fasts  of  5  to  14  days. 


METABOLISM  DURING  FASTING 


191 


There  is  likewise  usually  a  distinct  decrease  in  the  computed  24-hour 
heat-production  on  the  three  successive  days  of  each  fast.  Steers  E  and  F 
have  a  much  lower  heat-production  than  steers  C  and  D.  Thus,  on  the  first 
day  of  the  fast  the  older  steers  had  an  average  24-hour  heat-production  of 
about  11,600  calories,  and  the  younger  steers  of  about  7,550  calories.  This 
is  instantly  explainable  by  the  large  differences  in  body-weight,  for  the 
young  steers  actually  weighed  less  than  half  of  what  the  older  steers  weighed. 
Hence  we  are  quite  prepared  to  find  that  the  heat-production  of  steers  E 
and  F  per  500  kg.  of  body-weight  reflects  strikingly  the  influence  of  the 
younger  protoplasm. 

On  the  basis  of  uniformity  in  weight  a  decrease  in  the  heat-production 
still  appears,  although  it  so  happens  that  with  both  steers  E  and  F  the 
maximum  heat-production  per  500  kg.  of  body-weight  is  on  the  third  day. 
On  the  whole,  however,  the  differences  are  not  striking,  and  one  is  not  justi¬ 
fied  in  saying  that  the  heat-production  per  500  kg.  of  body-weight  under¬ 
goes  any  special  alteration  in  the  course  of  a  3-day  fast  beginning  24  hours 
after  the  withholding  of  food.  This  being  the  case,  it  is  not  surprising  that 
the  heat-production  per  square  meter  of  body-surface  usually  remains  uni¬ 
form  during  the  fast.  Steer  D  has  a  larger  heat-production  than  steer  C 
on  this  basis,  as  on  the  other  two  bases,  perhaps  accounted  for  by  his  dis¬ 
tinctly  greater  activity.  Steer  C  has  a  measurably  lower  heat-production 
per  square  meter  of  body-surface  than  the  younger  animals,  E  and  F,  but 
steer  D  has  essentially  the  same  heat-production  per  square  meter  of  body- 
surface  as  does  steer  F,  a  fact  which  might  be  cited  as  excellent  evidence  in 
favor  of  the  idea  of  uniformity  in  heat-production  per  square  meter  of 
body-surface.  Since  the  metabolism  of  steer  D  was  influenced  by  greater 
muscular  activity  than  was  the  case  with  steers  E,  F,  and  C,  the  metabolism 
of  steer  C  should  more  properly  be  compared,  perhaps,  with  that  of  steers 
E  and  F.  Such  comparison  shows  that  steer  C  has  a  much  lower  heat- 
production  per  square  meter  of  body-surface  than  either  steer  E  or  steer  F. 
The  average  heat-production  of  the  two  younger  animals,  on  this  basis,  is 
not  far  from  2,000  calories,  as  compared  with  an  average  value  of  1,670 
calories  in  the  case  of  steer  C.  In  other  words,  the  younger  animals  have 
a  metabolism  essentially  20  per  cent  higher  than  that  of  steer  C. 

These  fasting  values  may  be  compared  with  those  noted  in  Table  50  for 
the  heat-production  per  square  meter  of  body-surface  per  24  hours  in  the 
period  from  42  to  56  hours  after  the  last  food,  naturally  disregarding  the 
values  for  the  fast  in  March  1924.  The  average  heat-production  of  steer 
C  at  this  period  of  fasting  in  the  longer  fasts  was  1,730  calories  per  square 
meter  of  body-surface,  i.  e.,  essentially  the  same  as  the  average  value  of 
1,670  calories  found  in  the  3-day  experiment  in  April  1924.  Similarly  the 
somewhat  higher  values  noted  with  steer  D  in  Table  52  are  confirmed  by 
the  data  in  Table  50  for  the  long  fasts.  The  measurements  on  the  first  day 
of  the  long  fasts  were  made  22  to  32  hours  after  food,  and  those  on  the  first 
day  of  the  fast  in  May  1924  were  made  24  to  40  hours  after  food,  so  that 
the  time  interval  after  food  ingestion  is  essentially  the  same  in  both  cases. 
The  average  value  noted  for  steer  D  in  the  long  fasts,  omitting  that  in 
March  1924,  is  2,100  calories  as  compared  with  1,970  calories  on  May 


192 


METABOLISM  OF  THE  FASTING  STEER 


14,  1924.  For  the  second  day  the  average  value  in  the  long  fasts  is  slightly 
below  1,800  calories  as  compared  with  1,930  calories  on  the  second  day  of 
the  1924  experiment.  On  the  third  day  three  values  in  the  long  fasts  are 
around  1,800  calories,  the  remainder  being  all  perceptibly  below  1,800 
calories,  as  compared  with  1,900  calories  on  the  third  day  of  the  fast  in 
May  1924. 

These  comparisons  justify  the  conclusion  that  the  short  experiment  of 
four  half-hour  periods,  even  with  the  animal  standing  the  entire  time,  gives 
a  computed  heat-production  which  is  not  far  from  that  found  in  24-hour 
periods  when  the  animal  is  allowed  to  stand  or  lie  at  will.  From  the  criti¬ 
cisms  raised  against  the  short  period,  one  would  infer  that  the  values  com¬ 
puted  from  short  periods  would  in  general  be  higher  than  those  found  in 
long  periods.  This  is  not  the  case  in  the  comparisons  just  made.  It  is  true 
that  on  the  first  two  days  of  the  fast  of  steer  C  in  April  1924  values  slightly 
lower  than  the  average  values  on  the  first  two  days  of  the  long  fasts  are 
recorded,  but  in  the  fast  in  April  1924  steer  C  was  an  undernourished 
animal,  having  had  but  5  weeks  to  recover  from  a  10-day  fast  which  fol¬ 
lowed  a  long  period  of  submaintenance.  The  heat-production  of  steers  E 
and  F  on  the  several  bases  of  computation  was  higher  in  the  continuous 
3-day  experiments  than  in  the  fasting  experiments  of  February  1924,  fol¬ 
lowing  submaintenance  feeding.  Unfortunately,  no  fasting  experiments 
were  made  with  steers  E  and  F  following  maintenance  feeding,  on  the  basis 
of  four  half-hour  periods  of  measurement. 

So  far  as  the  evidence  goes,  it  points  toward  the  legality  of  computing  the 
fasting  metabolism  from  four  half-hour  periods  of  measurement.  Indeed, 
the  justification  for  the  use  of  the  half-hour  period  is  far  greater  in  the  case 
of  fasting  experiments  than  it  would  be  in  the  case  of  experiments  when  the 
animals  receive  food  regularly,  for  in  the  transitional  stage  following  the 
digestion  of  food  the  peak  of  digestive  activity  occurs  at  different  periods, 
depending  upon  the  nature  and  the  amount  of  food  ingested.  We  have  not 
studied  food  problems  in  experiments  of  four  half-hour  periods,  but  we  have 
used  the  short  half-hour  periods  in  studying  the  influence  of  the  ingestion 
of  food,  that  is,  the  rapidity  of  digestive  activity  and  the  increment  in 
metabolism  due  to  such  activity.  These  experiments  will  be  considered 
subsequently  (see  p.  222). 

Comparison  of  the  Metabolism  During  2  Days  on  Food,  Followed  by  2 

Days  Without  Food,  at  Maintenance  and  Submaintenance  Levels 
and  at  High  and  Low  Environmental  Temperatures 

The  state  of  nutrition  has  not  been  seriously  considered,  at  least  in  the 
case  of  humans,  as  affecting  the  fasting  metabolism,  but  our  experience 
with  steers  in  the  series  of  long  and  short  fasts  indicated  that  the  nutritive 
level  at  which  the  fast  begins  has  a  great  influence  upon  the  fasting 
metabolism.  To  study  specifically  the  influence  of  different  feed-levels, 
therefore,  a  series  of  4-day  respiration  experiments  were  made  with  steers 
E  and  F  in  1925.  The  animals  were  confined  in  the  respiration  chamber  as 
they  would  be  in  a  stall  in  the  barn,  and  were  allowed  to  stand  and  lie  at 
will.  During  the  first  two  days  they  received  feed  and  drinking-water  as 


METABOLISM  DURING  TWO  FEED  DAYS  AND  TWO  FASTING  DAYS  193 

usual.  During  the  last  two  days  no  feed  was  given,  but  water  was  offered 
as  usual.  In  some  experiments  a  maintenance  ration  of  hay  was  given  on 
the  2  feed  days  and  in  others  a  submaintenance  ration,  the  animals  having 
been  upon  the  particular  feed-level  under  consideration  for  at  least  2  weeks 
prior  to  the  respiration  experiment.  The  ration  was,  furthermore,  altered 
not  only  with  regard  to  the  quantity  of  metabolizable  energy,  but  also  quali¬ 
tatively  with  regard  to  the  character  of  the  feed,  timothy  hay  being  fed  in 
some  experiments  and  alfalfa  hay  in  others.  The  selection  of  the  timothy 
and  alfalfa  hay,  however,  was  not  made  for  the  purpose  of  considering  the 
relative  merits  of  these  two  feedstufifs  for  maintenance  or  for  preparing  the 
animal  to  resist  a  fast,  but  because  these  two  substances  are  by  common 
consent  considered  typically  different  in  character,  and  it  was  desired,  if 
possible,  to  alter  considerably  the  character  as  well  as  the  quantity  of  the 
ration. 

The  effect  of  extreme  variations  in  environmental  temperature  was  also 
introduced  in  this  series  of  4-day  experiments.  In  the  earlier  series  of  short 
fasts  the  influence  of  environmental  temperature  had  been  studied,  but  it 
was  believed  that  in  that  series  the  picture  of  the  effect  of  the  environmental 
temperature  reflected  only  the  first  reaction  of  the  animal  to  a  sudden 
change  in  temperature.  Hence,  in  the  1925  series  the  animal  was  purposely 
kept  for  approximately  two  weeks  in  a  stall  temperature  essentially  the 
same  as  that  which  was  to  be  maintained  in  the  respiration  chamber  during 
the  4-day  experiment.  Environmental  temperatures  varying  from  23.3°  C. 
to  as  low  as  3.6°  C.  were  accordingly  studied.  So  far  as  the  comparison  of 
timothy  and  alfalfa  hay  is  concerned,  the  data  are  reasonably  complete  for 
both  steers.  Uncontrollable  conditions  with  regard  to  the  temperature, 
however,  made  it  impossible  at  times  to  secure  as  low  a  temperature  and  as 
satisfactory  uniformity  in  temperature  control  as  was  wished.  The  data  in 
this  respect,  therefore,  are  not  complete  for  steer  F,  but  are  fortunately 
more  complete  for  steer  E  both  at  the  maintenance  and  submaintenance 
levels  of  nutrition. 

The  influence  of  a  maintenance  and  submaintenance  level  of  nutrition  and 
of  two  different  feedstuffs  upon  the  metabolism  both  during  feeding  and 
fasting  was  thus  determined.  Furthermore,  the  plan  of  the  experiments 
made  it  possible  to  secure  evidence  as  to  the  accuracy  of  the  method  of 
computing  the  fasting  katabolism  from  the  measured  metabolism  of  the 
animal  when  upon  two  different  feed-levels.  Indeed,  one  of  the  main 
objects  of  the  experiments  was  to  obtain  information  on  this  point.  Other 
evidence  was  furnished  by  this  series  of  experiments  regarding  the  influence 
of  the  nutritive  level,  the  character  of  the  feed,  and  the  environmental  tem¬ 
perature  upon  the  metabolism  during  the  transitional  stage  on  the  first  day 
of  fasting.  It  was  believed  that  the  profound  effect  of  the  submaintenance 
ration  upon  the  level  of  the  fasting  metabolism  would  be  reflected  somewhat 
in  the  metabolism  when  the  animal  was  receiving  submaintenance  rations, 
and  particularly  in  the  transitional  stage  on  the  first  day  of  fasting.  Indeed, 
the  measurement  of  the  metabolism  during  this  transitional  period  would 
serve  to  indicate  the  value  of  the  different  types  of  feed  and  of  the  two 
different  nutritive  levels  in  enabling  the  animal  to  withstand  the  fast, 


194 


METABOLISM  OF  THE  FASTING  STEER 


inasmuch  as  it  would  give  an  idea  as  to  the  rapidity  and  intensity  of  the 
drafts  upon  the  body  compounds.  In  addition,  the  determination  of  the 
actual  level  to  which  the  metabolism  falls  during  two  days  of  fasting  should 
furnish  an  excellent  control  upon  the  earlier  measurements  made  in  short 
half-hour  periods  and,  indeed,  should  compare  reasonably  well  with  the 
level  noted  in  the  continuous  3-day  fasting  experiments  made  in  the  spring 
of  1924. 

The  data  secured  with  steers  E  and  F  during  this  series  of  4-day  experi¬ 
ments  are  summarized  in  Table  53.  Each  day  began  at  4h  30m  p.  m.  The 
carbon-dioxide  production  was  determined  quantitatively  in  two  8-hour 
periods  and  two  4-hour  periods  each  day.  The  residual  air  inside  the  res¬ 
piration  chamber  was  analyzed  at  the  end  of  each  period,  and  the  respiratory 
quotient  was  determined  for  nearly  every  period.  The  data  are  therefore 
available  for  computing  the  heat-production  during  each  of  the  8-hour 
periods  as  well  as  during  the  entire  24-hour  periods.  Space  does  not  permit 
the  printing  of  all  the  8-hour  values,  unfortunately,  and  in  Table  53  only 
the  24-hour  values  have  been  recorded.  It  is  believed,  however,  that  the 
picture  of  the  metabolism  under  the  special  conditions  studied  will  be  best 
illustrated  by  these  24-hour  values,  since  the  difficulty  of  working  with  a 
non-cooperating  ruminant  makes  the  use  of  the  8-hour  period,  particularly 
during  feed  days  and  in  the  transitional  stage  from  feeding  to  fasting,  of 
questionable  value.  If  it  were  possible  to  rule  out  muscular  activity  while 
studying  the  metabolism  during  the  first  48  hours  after  the  withholding 
of  food,  then  a  4-hour  or  8-hour  period  of  measurement  would  be  of  great 
importance. 

In  accordance  with  the  method  of  calculation  employed  in  presenting  the 
energy  values  in  the  earlier  fasts,  the  heat-production  during  these  4-day 
experiments  has  been  computed  from  the  carbon-dioxide  production  and  the 
respiratory  quotient  in  all  cases  where  the  respiratory  quotient  was  1.00  or 
below,  and  from  the  computed  oxygen  consumption  and  the  calorific  value 
of  oxygen  at  a  quotient  of  1.00  in  those  cases  where  the  respiratory  quotient 
was  above  1.00.  (See  pp.  147  to  150.)  The  heat  values  are  reported  on  the 
three  bases  of  the  total  heat-production  per  24  hours  and  the  24-hour  heat- 
production  per  500  kg.  of  body-weight  and  per  square  meter  of  body-surface. 

It  was  impossible  to  weigh  the  animal  except  at  the  beginning  and  end 
of  these  experiments.  Hence  the  body-weights  on  the  intermediate  days 
are  interpolated,  on  the  assumption  that  during  the  first  two  days  with  feed 
the  body-weight  would  remain  unchanged  and  that  on  the  first  fasting  day 
there  would  be  a  decrease  equivalent  to  the  amount  of  the  daily  ration 
withheld.  The  body-weight  reported  in  Table  53  for  the  first  day  of  each 
experiment  is  not,  however,  the  weight  on  that  particular  day,  but  is  an 
average  weight  based  upon  the  weight  on  that  day  and  on  6  days  preceding. 
The  urine  voided  was  collected  each  day  with  but  few  exceptions.  The 
feces  could  not  be  collected  daily  and  were  allowed  to  accumulate  in  a  large, 
air-tight  container  underneath  the  respiration  chamber  (see  Fig.  2,  p.  26). 

In  the  belief  that  there  would  be  a  distinct  difference  in  the  general 
physical  activity  of  the  animal  on  days  with  feed  and  days  without  feed, 
kymograph  records  of  the  degree  of  activity  were  kept  and  an  approximate 


METABOLISM  DURING  TWO  FEED  DAYS  AND  TWO  FASTING  DAYS  195 


Table  53. — Summary  of  4-day  respiration  experiments  with  steers  E  and  F 


Steer  and  date1 
(1924-25) 

Live 

weight 

Hours 

standing 

Hours 

lying 

Hay 
eaten 
in  24 
hours2 

Hours 

without 

food 

to 

begin¬ 
ning  of 
day 

Average 

stall 

temper¬ 

ature 

week 

before 

experi¬ 

ment 

Average 

chamber 

temper¬ 

ature 

Heat  produced  per  24  hours 

Total 

Per 

500  kg. 

Per 
sq.  m. 

Steer  E : 

kg. 

kg. 

°C. 

°C. 

cal. 

cal. 

cal. 

Dec.  12-13 . 

368.8 

14 

10 

7.0 

0 

24 

22.5 

11,800 

16,000 

2,720 

Dec  13-14. 

(368.8) 

11 

13 

7.0 

0 

22.5 

11,500 

15,600 

2,650 

Dec  14-15  . 

(361.8) 

9)4 

14)4 

0.0 

8 

22.2 

8,900 

12,300 

2,070 

349.4 

7  )4 

16}4 

0.0 

32 

22.1 

7,700 

11,000 

1,830 

Jan.  13-14 . 

351.4 

13 

11 

3.5 

0 

25 

22.3 

8,200 

11,700 

1,940 

Jan.  14-15  . 

(351.4) 

10  Yi 

13J4 

3.5 

0 

22.7 

7,900 

11,200 

1,870 

(348.0) 

10)4 

13)4 

0.0 

24 

22.6 

6,800 

9,800 

1,620 

Jan  16-17 . 

333.4 

12  y2 

11)4 

0.0 

48 

22.6 

6,000 

9,000 

1,470 

Feb.  2-  3 . 

337.6 

17  'A 

6)4 

3.5 

0 

4 

4.7 

9,000 

13,300 

2,190 

Feb  3-  4 

(337.6) 

11 

13 

3.5 

0 

5.1 

9,200 

13,600 

2,240 

Feb  4-  5  . 

(333.8) 

17 

7 

0.0 

24 

5.7 

7,200 

10,800 

1,760 

Feb.  5-6 _ 

322.8 

11)4 

12J4 

0.0 

48 

8.8 

6,500 

10,100 

1,630 

Feb.  27-28 . 

359.0 

10)4 

13)4 

7.0 

0 

11 

3.6 

11,000 

15,300 

2,580 

Feb.  28-Mar.  1...  . 

(359.0) 

9 

15 

7.0 

0 

6.1 

11,200 

15,600 

2,620 

(352.0) 

8)4 

15)^ 

0.0 

8 

9.6 

8,800 

12,500 

2,090 

338.2 

12 

12 

0.0 

32 

4.6 

7,800 

11,500 

1,900 

Mar.  16-17 . 

352.8 

11 

13 

7.0 

0 

23 

21.7 

11,600 

16,400 

2,740 

Mar  17-18  . 

(352.8) 

10)4 

1314 

7.0 

0 

22.0 

11,400 

16,200 

2,700 

Mar  18-19 . 

(345.8) 

7  )4 

16)4 

0.0 

8 

21.6 

8,300 

12,000 

1,990 

Mar.  19-20.. 

339.0 

8 

16 

0.0 

32 

22.3 

7,000 

10,300 

1,700 

Apr.  14-15 . 

362.8 

13H 

10)4 

7.0 

0 

22 

22.9 

11,500 

15,800 

2,670 

(355.8) 

4 

20 

0.0 

8 

21.8 

7,600 

10,700 

1,790 

Apr.  16-17 

350.4 

6)4 

17)4 

0.0 

32 

21.7 

6,700 

9,600 

1,590 

May  4-  5 . 

346.6 

9M 

14)4 

3.5 

0 

23 

22.6 

7,800 

11,300 

1,860 

(346.6) 

9)4 

14)4 

3.5 

0 

22.1 

7,700 

11,100 

1,840 

(343.2) 

7)4 

16)4 

0.0 

24 

22.2 

5,400 

7,900 

1,300 

May  7-  8 

339.0 

9  )4 

14)4 

0.0 

48 

22.0 

5,500 

8,100 

1,330 

Steer  F: 

Dec.  17-18 . 

435.2 

9 

15 

7.0 

0 

23 

22.5 

11,900 

13,700 

2,470 

Dec  18-IP  . 

(435.2) 

11 

13 

7.0 

0 

22.3 

11,900 

13,700 

2,470 

Dec  19-20 

(428.2) 

9 14 

14)4 

0.0 

8 

22.4 

9,300 

10,900 

1,950 

Dec  20-21 

415.8 

7)4 

16)4 

0.0 

32 

21.3 

8,100 

9,700 

1,730 

Jan.  19-20 . 

408.6 

14 

10 

3.5 

0 

24 

21.9 

9,200 

11,300 

1,990 

(408.6) 

10 

14 

3.5 

0 

22.2 

8,800 

10,800 

1,900 

(405.2) 

10 

14 

0.0 

24 

22.3 

7,100 

8,800 

1,540 

399.6 

10  )4 

13)4 

0.0 

48 

21.7 

6,500 

8,100 

1,420 

Feb.  13-14 . 

394.6 

13 

11 

3.5 

0 

13 

9.2 

9,400 

11,900 

2,070 

Feb  14-15 

(391.2) 

11 

13 

0.0 

24 

10.2 

7,500 

9,600 

1,660 

Feb.  15-16. 

383.2 

12 

12 

0.0 

48 

10.6 

7,000 

9,100 

1,570 

Mar.  23-24 . 

423.2 

13  )4 

10)4 

7.0 

0 

25 

22.1 

12,500 

14,800 

2,640 

Mar  24-25 

(423.2) 

10)4 

13)4 

7.0 

0 

22.5 

12,600 

14,900 

2,660 

(416.2) 

9)4 

14^ 

0.0 

8 

22.7 

9,100 

10,900 

1,940 

Mar  26-27 

399.8 

10J4 

13H 

0.0 

32 

22.2 

7,700 

9,600 

1,680 

Apr.  20-21 . 

424.0 

11 

13 

7.0 

0 

21 

22.5 

12,300 

14,500 

2,590 

Apr.  21-22  . 

(424.0) 

li)4 

12)4 

7.0 

0 

22.3 

12,300 

14,500 

2,590 

(417.0) 

9J4 

14)4 

0.0 

8 

23.3 

8,700 

10,400 

1,860 

Apr.  23-24 

(410.0) 

(8) 

(8)' 

0.0 

32 

21.7 

7,500 

9,100 

1,620 

Apr  24-25 

4  404 . 2 

4  8 

4  8 

0.0 

56 

22.4 

7,600 

9,400 

1,650 

May  11-12 . 

407.0 

12)4 

11)4 

3.5 

0 

21 

22.0 

9,100 

11,200 

1,970 

May  12-13 

(407  0) 

13 

11 

3.5 

0 

23.2 

9,000 

11,100 

1,950 

May  13-14 

(403.5) 

8)4 

15)4 

0.0 

24 

22.7 

6,300 

7,800 

1,370 

May  14-15 . 

392.6 

11  ” 

13 

0.0 

48 

21.7 

6,200 

7,900 

1,370 

1  Beginning  and  ending  at  4h  30m  p.  m. 

*  Timothy  hay  fed  to  both  steers,  until  Mar.  6,  1925,  in  the  case  of  steer  E,  and  Mar.  9,  1925,  in  the  case 

of  steer  F;  alfalfa  hay  fed  thereafter. 

*  Records  incomplete  for  24  hours. 

4  Experiment  only  16  hours  long.  Data  computed  to  24-hour  basis. 


196 


METABOLISM  OF  THE  FASTING  STEER 


assessment  of  the  quantitative  degree  of  activity  has  been  made  for  each 
of  the  different  experimental  periods.  In  discussing  the  result  we  shall 
therefore  be  able  to  state  with  considerable  confidence  whether  the  activity 
was  materially  different  on  the  different  days  of  the  experiments.  Complete 
records  with  regard  to  the  number  of  hours  spent  in  lying  and  standing  were 
also  secured  and  are  given  in  Table  53. 

The  two  animals  used  for  this  work  were  essentially  of  the  same  age  and 
size,  although  steer  E  was  actually  somewhat  smaller  than  steer  F,  weighing 
369  kg.  at  the  beginning  of  the  series  of  experiments  as  compared  with  steer 
F’s  weight  of  435  kg.  Both  animals,  in  the  period  from  December  1924  to 
May  1925  lost  about  30  kg.  as  a  result  of  the  winter’s  experimental  regime, 
which  included  13  or  14  intermittent  fasting  days.  A  general  effort  was 
made  between  the  fasts  to  make  up  in  part  for  the  lost  feed,  but  it  is  clear 
that  there  was  not  complete  compensation,  as  is  shown  by  the  loss  in  body- 
weight. 

Influence  of  Quantity  and  Character  of  Ration  Upon  Metabolism  During  Feeding 

These  4-day  experiments  were  made  primarily  to  study  the  effect  of 
fasting  upon  the  metabolism,  but,  in  the  attempt  to  establish  standard 
feeding  conditions  prior  to  the  fasting,  information  was  also  secured  regard¬ 
ing  the  metabolism  during  maintenance  and  submaintenance  feeding  with 
two  different  kinds  of  hay,  timothy  and  alfalfa.  Their  influence  upon  the 
metabolism  is  of  special  interest,  owing  to  the  great  economic  problems 
involved  in  the  rationing  of  domestic  animals.  It  is  not  our  purpose,  how¬ 
ever,  to  enter  into  an  extensive  treatment  of  the  economic  value  of  these 
two  feedstuffs,  for  the  feeding  experiments  were  not  made  primarily  with  this 
in  view.  The  observations  are  of  significance,  however,  in  indicating  the 
nutritive  plane  of  the  animal  prior  to  the  complete  withdrawal  of  food  and 
furnish  a  base-line  for  the  study  of  the  effect  of  fasting. 

Ib  Table  53  the  values  for  the  total  heat-production  per  24  hours  have 
been  recorded,  but  since  steers  E  and  F  differed  somewhat  in  weight,  this 
discussion  will  be  confined  to  a  consideration  of  the  heat-production  per 
500  kg.  of  body-weight  per  24  hours.  The  picture  will  be  essentially  the 
same  with  the  heat-production  per  square  meter  of  body-surface  per  24 
hours,  but  the  consideration  of  these  values  will  be  deferred  for  later,  more 
critical  analysis  from  another  point  of  view  (see  pp.  218  to  222). 

The  effect  upon  the  heat-production  of  a  maintenance  ration  of  7  kg.  of 
hay  was  studied  with  steer  E  on  four  occasions.  In  two  cases  the  ration 
consisted  of  timothy  hay  and  in  two  cases  of  alfalfa  hay.  With  steer  F 
one  experiment  was  made  with  a  maintenance  ration  of  timothy  hay  and 
two  experiments  were  made  with  a  maintenance  ration  of  alfalfa  hay.  In 
all  but  one  instance,  i.  e.,  on  February  27  to  March  1  with  steer  E,  the 
environmental  temperature  was  essentially  22°  C.,  and  for  the  moment, 
therefore,  the  effect  of  environmental  temperature  may  be  disregarded. 
When  steer  E  was  on  a  maintenance  ration,  the  heat-production  per  500  kg. 
of  body-weight  per  24  hours  ranged  from  15,300  to  16,400  calories,  the 
higher  values  being  noted  with  the  alfalfa  hay.  With  steer  F  the  values 
range  from  13,700  to  14,900  calories,  the  alfalfa  hay  again  resulting  in  a 


METABOLISM  DURING  TWO  FEED  DAYS  AND  TWO  FASTING  DAYS  197 

higher  heat-production.  Both  animals,  therefore,  have  essentially  a  some¬ 
what  higher  heat-production  with  the  maintenance  ration  of  alfalfa  hay. 

The  smallness  of  our  staff  made  it  impossible  to  carry  out  complete 
digestion  experiments  and  nitrogen  metabolism  experiments,  and  the  metabo¬ 
lizable  energy  in  these  two  different  rations  could  not  be  determined.  There 
is  little,  if  any,  reason  to  believe,  however,  that  such  determinations  would 
materially  alter  the  conclusions  as  presented,  for  we  are  dealing  here  with 
the  heat-production,  under  the  same  conditions,  of  animals  which  are  seem¬ 
ingly  strictly  comparable.  It  should  be  pointed  out,  however,  that  alfalfa 
hay  is  nitrogen-rich  and  timothy  hay  is  nitrogen-poor,  and  that  undoubtedly 
on  timothy  hay,  and  possibly  on  alfalfa  hay,  the  animals  were  actually 
losing  nitrogen.0 

Since  these  experiments  were  planned  primarily  to  note  the  effect  of  main¬ 
tenance  and  submaintenance  feed-levels  and  variations  in  environmental 
temperature  upon  the  metabolism  during  feeding  and  fasting,  the  compari¬ 
son  of  the  influence  of  timothy  and  alfalfa  hay  was  only  an  incidental  study. 
The  discussion  of  the  influence  of  these  hays  upon  the  metabolism  at  the 
submaintenance  level  is  therefore  somewhat  complicated  by  the  fact  that 
in  these  submaintenance  experiments  marked  differences  in  temperature 
designedly  prevailed.  We  will  consider  for  the  moment,  therefore,  only 
those  submaintenance  experiments  in  which  the  chamber  temperature  was 
not  far  from  20°  C. 

When  a  submaintenance  ration  of  3.5  kg.  of  either  timothy  or  alfalfa  hay 
was  given,  the  metabolic  level  of  both  steers  during  feeding  was  lowered 
decidedly.  Thus,  we  find  that  with  steer  E  the  24-hour  heat-production 
per  500  kg.  of  body-weight  during  feeding  with  timothy  hay  has  changed 
from  an  average  maintenance  level  of  15,800  calories  on  December  12-13 
and  December  13-14  to  an  average  submaintenance  level  of  11,500  calories 
on  January  13-14  and  January  14-15.  With  alfalfa  hay,  the  metabolism 
has  fallen  from  a  maintenance  level  of  15,800  calories  on  April  14-15  to  a 
submaintenance  level  of  11,200  calories  on  May  4-5  and  May  5-6.  With 
steer  F  the  24-hour  heat-production  per  500  kg.  of  body-weight  during 
maintenance  feeding  on  timothy  hay  was  13,700  calories  on  December  17-18 
and  December  18-19,  but  fell  with  submaintenance  feeding  to  an  average 
of  11,000  calories  on  January  19-20  and  January  20-21.  With  alfalfa  hay 
the  maintenance  level  in  April  was  14,500  calories  and  the  submaintenance 
level  in  May  was  11,200  calories. 

From  these  data  it  can  be  seen  that  the  submaintenance  level  of  metabo¬ 
lism  was  much  lower  than  the  maintenance  level  in  the  case  of  both  steers. 
Moreover,  the  submaintenance  level  of  metabolism  was  essentially  the  same 
with  both  steers,  regardless  of  the  character  of  the  hay,  but  since  the  main¬ 
tenance  level  of  metabolism  of  steer  E  was  greater  than  that  of  steer  F,  the 
fall  in  his  metabolism  to  the  submaintenance  level  is  somewhat  more  pro¬ 
nounced.  The  fall  in  metabolism  with  both  steers  is  slightly  greater  with 
alfalfa  than  with  timothy  hay.  In  view  of  the  well-known  difficulties  of 


*  Armsby  and  Fries,  (U.  S.  Dept.  Agric.,  Bureau  Animal  Industry  Bull.  51,  1903,  p.  9)  found 
that  timothy  hay  was  too  poor  in  protein  to  be  used  as  a  maintenance  ration  and  added  linseed 
meal  to  the  ration. 


198 


METABOLISM  OF  THE  FASTING  STEER 


making  direct  comparisons  of  the  heat-production  of  animals  with  which 
digestion  experiments  are  not  simultaneously  carried  out,  conservative  treat¬ 
ment  of  these  findings  is  necessary.  In  the  submaintenance  experiments, 
undoubtedly  both  animals  were  losing  nitrogen  heavily.  From  our  earlier 
research  on  undernutrition  in  steers,  in  which  we  found  that  submaintenance 
feeding  did  not  materially  alter  the  digestibility  of  the  ration,0  it  is  assumed, 
however,  that  the  digestibility  of  the  feed  remained  essentially  the  same  as 
it  was  when  the  steers  were  on  maintenance  rations. 

Influence  of  Quantity  and  Character  of  Ration  Upon  Metabolism  During  Fasting 

For  the  study  of  fasting  per  se,  the  metabolism  measurements  on  the  two 
days  of  fasting  in  the  several  experiments  claim  our  greatest  attention. 
Considering  again  the  heat-production  per  500  kg.  of  body-weight,  we  note 
that  as  usual  in  all  of  the  experiments  the  heat-production  on  this  basis 
decreased  markedly  on  the  fasting  days  and  was  in  general  lower  on  the 
second  of  the  two  days.  From  our  analysis  of  the  data  for  the  longer  fasts, 
however,  it  is  obvious  that  a  still  further  reduction  in  the  heat-production 
would  occur  if  the  fast  were  prolonged  beyond  two  days,  and  that  undoubt¬ 
edly  at  the  end  of  two  days  the  period  of  true  fasting  (i.  e.,  when  the  con¬ 
tributions  from  the  feed  residues  in  the  intestinal  tract  would  have  prac¬ 
tically  ceased)  has  not  yet  been  reached. 

The  metabolism  on  the  first  day  of  fasting  following  submaintenance 
feeding  was  lower  than  that  following  maintenance  feeding.  According  to 
the  experimental  plan  in  these  4-day  experiments,  however,  the  first  day 
of  fasting  following  maintenance  rations  represents  a  period  beginning  8 
hours  after  the  last  feed  and  continuing  until  32  hours  after  the  last  feed. 
Following  submaintenance  rations,  it  represents  a  period  beginning  24  hours 
and  continuing  until  48  hours  after  feed.  These  differences  in  the  time 
represented  by  the  first  day  of  fasting  are  due  to  the  differences  in  feed-level. 
Thus,  in  the  submaintenance  experiments,  feed  was  given  only  once  a  day 
and  at  such  a  time  during  the  day  as  to  bring  the  beginning  of  the  third 
experimental  day  (or  the  first  day  of  fasting)  24  hours  after  the  last  feed. 
In  the  maintenance  experiments  the  feed  was  given  twice  a  day,  and  the 
first  day  of  fasting  therefore  began  only  8  hours  after  feed.  It  is  important 
to  bear  this  in  mind  in  the  interpretation  of  the  results,  for  in  the  submain¬ 
tenance  experiments  the  fasting-period  is  distinctly  longer  than  in  the  main¬ 
tenance  experiments.  Hence  the  markedly  lower  metabolism  found  on  the 
first  day  of  fasting  in  the  submaintenance  experiments  may  be  in  part 
accounted  for  by  the  fact  that  this  day  represents  a  later  period  in  the  fast 
than  does  the  first  day  of  fasting  in  the  maintenance  experiments. 

The  influence  of  the  character  of  the  hay  upon  the  actual  fasting  metabo¬ 
lism  at  the  different  nutritive  levels  may  best  be  compared  by  considering 
only  those  experiments  in  which  the  environmental  temperature  is  similar. 
On  the  first  day  of  fasting  after  maintenance  feeding  with  timothy  hay  the 
heat-production  of  steer  E  per  500  kg.  of  body-weight  is  12,300  calories. 
This  drops  on  the  second  day  to  11,000  calories.  Under  similar  conditions 
with  alfalfa  hay,  the  metabolism  is  12,000  calories  on  the  first  day  of  fasting 


°  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  131. 


METABOLISM  DURING  TWO  FEED  DAYS  AND  TWO  FASTING  DAYS  199 


and  drops  to  10,300  calories  on  the  second  day.  The  decrease  is  thus  1,300 
calories  in  the  first  case  and  1,700  calories  in  the  second  case.  In  a  second 
experiment  with  steer  E  with  alfalfa  hay  (April  14  to  17)  the  decrease  is 

I, 100  calories  from  the  first  to  the  second  day  of  fasting. 

With  steer  F  there  was  a  drop  of  1,200  calories  from  the  first  to  the  second 
day  of  fasting  in  the  December  fast,  following  a  maintenance  ration  of 
timothy  hay.  In  the  March  fast  following  the  maintenance  ration  of  alfalfa 
hay  there  was  a  decrease  of  1,300  calories,  and  in  the  April  fast  under  the 
same  conditions  a  fall  of  1,300  calories.  In  this  latter  fast  the  metabolism 
was  also  measured  for  the  first  16  hours  of  the  third  day  of  fasting,  and  has 
been  computed  to  the  24-hour  basis.  No  appreciable  difference  in  metabo¬ 
lism,  however,  is  to  be  observed  between  the  second  and  third  days  of  fasting 
in  this  April  fast  with  steer  F. 

In  general,  distinctly  lower  values  are  found  on  the  two  fasting  days  fol¬ 
lowing  maintenance  feeding  with  alfalfa  hay  than  following  maintenance 
feeding  with  timothy  hay. 

In  the  submaintenance  experiments  at  or  about  20°  C.,  essentially  the 
same  metabolism  per  500  kg.  of  body-weight  was  noted  during  the  two  feed 
days,  with  both  hays  and,  indeed,  with  both  animals,  i.  e.,  not  far  from 

II, 000  calories  per  24  hours.  On  the  first  day  of  fasting,  that  is,  24  to  48 
hours  after  food,  steer  E  had  a  metabolism  of  9,800  calories  following  the 
submaintenance  ration  of  timothy  hay  and  7,900  calories  following  the 
ration  of  alfalfa  hay.  With  steer  F  the  corresponding  figures  are  8,800 
calories  and  7,800  calories,  respectively.  Thus,  both  animals  have  a  strik¬ 
ingly  lower  level  of  metabolism  following  a  submaintenance  ration  of  alfalfa 
hay.  On  the  second  day  of  fasting,  in  the  same  series  of  experiments,  steer 
E  had  a  heat-production  of  9,000  calories  following  the  submaintenance 
ration  of  timothy  hay  in  January  and  8,100  calories  following  the  alfalfa 
hay.  Steer  F  produced  8,100  calories  on  the  second  day  of  fasting  following 
a  submaintenance  ration  of  timothy  hay  in  January  and  7,900  calories  fol¬ 
lowing  a  submaintenance  ration  of  alfalfa  hay  in  May.  There  is  therefore 
also  a  distinctly  lower  metabolism  with  both  of  these  animals  on  the  second 
day  of  fasting  at  the  submaintenance  level  with  alfalfa  hay.  It  is  to  be 
observed,  however,  that  in  the  May  experiments  with  both  animals,  essen¬ 
tially  the  same  values  were  noted  on  the  two  days  of  fasting,  there  being  a 
slight  rise  on  the  second  day. 

The  general  picture  of  the  influence  of  the  two  different  feeds  upon  the 
fasting  level  of  metabolism,  in  experiments  at  environmental  temperatures 
ranging  close  to  20°  C.,  is  that  the  fasting  metabolism  of  both  animals  was 
decidedly  lower  after  alfalfa  hay  than  after  timothy  hay  and  that  this 
relationship  persisted  into  the  second  day  of  fasting.  Thus  we  have  clear 
evidence  that  following  a  ration  of  alfalfa  hay,  the  nutritive  level  of  the 
animal  calls  for  a  fasting  metabolism  actually  less  than  that  following  a 
ration  of  timothy  hay,  whether  the  ration  is  a  maintenance  or  a  submain¬ 
tenance  one.  It  is  obvious  that  for  the  complete  control  of  this  finding, 
experiments  are  highly  desirable  in  which  it  is  clearly  established  that  the 
animals  are  in  nitrogen  equilibrium  on  the  full  maintenance  ration.  On 
submaintenance  rations  nitrogen  loss  is  inevitable. 


200 


METABOLISM  OF  THE  FASTING  STEER 


Influence  of  Environmental  Temperature 

Our  earlier  results  on  the  influence  of  environmental  temperature  were, 
on  the  whole,  of  such  nature  as  to  warrant  the  conclusion  that  the  tempera¬ 
ture  of  the  environment  has  no  material  influence  on  heat-production  under 
ordinary  conditions,  although  some  of  the  data  did  suggest  that  with  the 
lower  temperature  there  was  actually  less  heat  produced.  In  the  series  of 
4-day  experiments  reported  in  Table  53,  there  is  clear-cut  evidence  of  a 
pronounced  influence  of  temperature  upon  the  metabolism  when  the  other 
factors  which  might  influence  the  metabolism  remain  essentially  constant. 
This  is  particularly  true  in  the  case  of  the  submaintenance  experiments  in 
January  and  February  with  steer  E,  when  timothy  hay  was  fed.  The  second 
of  these  two  experiments  was  made  at  a  much  lower  temperature  (on  the 
average  nearly  17  degrees  lower)  than  the  first,  and  the  heat-production  per 
500  kg.  of  body-weight  was  actually  considerably  higher  at  the  lower  tem¬ 
perature.  Thus,  on  the  first  two  days  with  feed  at  the  higher  temperature  of 
22°  C.  the  heat-production  was  11,700  and  11,200  calories  per  500  kg.  of 
body-weight.  When  the  temperature  was  4.7°  and  5.1°  C.,  respectively, 
the  heat-production  on  the  two  feed  days  rose  to  13,300  and  13,600  calories, 
an  increase  of  approximately  17  per  cent.  On  the  first  day  of  fasting  fol¬ 
lowing  the  submaintenance  ration  the  heat-production  per  500  kg.  of  body- 
weight  was  9,800  calories  at  the  higher  temperature  and  10,800  calories,  or 
11  per  cent  higher,  at  the  low  temperature  of  5.7°  C.  On  the  second  fasting 
day  the  metabolism  was  9,000  calories  at  22.6°  C.  and  10,100  calories  at 
8.8°  C.,  or  12  per  cent  higher.  These  experiments  show  definitely,  therefore, 
that  the  influence  of  environmental  temperature  at  the  submaintenance  level 
is  noticeable,  and  that  a  difference  of  17  degrees  in  the  temperature  has 
made  a  difference  of  not  far  from  17  per  cent  in  the  metabolism,  i.  e.,  a 
difference  of  1  per  cent  in  the  metabolism  for  a  change  of  1°  C.  in  tem¬ 
perature.  The  picture  is  not  materially  altered  when  the  heat-production 
is  computed  per  square  meter  of  body-surface,  the  cold  temperatures  result¬ 
ing  in  distinctly  higher  values. 

With  steer  F,  a  comparison  of  high  and  low  environmental  temperatures 
was  likewise  made  in  connection  with  his  two  submaintenance  experiments 
in  January  and  February,  with  timothy  hay.  In  the  January  experiment 
the  average  chamber  temperature  was  about  22°  C.  and  in  the  February 
experiment  it  was  about  10°  C.  The  difference  in  temperature  was  there¬ 
fore  not  so  great  as  in  the  case  of  steer  E,  and  the  experiment  at  the  lower 
temperature  included  only  one  day,  February  13-14,  with  feed.  On  this 
day  the  heat-production  per  500  kg.  of  body-weight  was  actually  7  per  cent 
higher  than  the  average  heat-production  on  the  two  feed  days  in  the  January 
experiment.  On  the  first  day  of  fasting  the  metabolism  at  the  lower  tem¬ 
perature  was  9  per  cent  higher  and  on  the  second  day  of  fasting  12  per  cent 
higher. 

With  the  two  animals  the  picture  of  the  influence  of  environmental  tem¬ 
perature  under  submaintenance  conditions  is  essentially  the  same.  The 
effect  is,  however,  apparently  not  proportional  to  the  difference  in  tem¬ 
perature,  at  least  so  far  as  can  be  judged  from  experiments  with  two  differ¬ 
ent  animals,  for  in  the  case  of  steer  F  the  influence  of  a  change  in  tempera- 


METABOLISM  DURING  TWO  FEED  DAYS  AND  TWO  FASTING  DAYS  201 

ture  of  approximately  12  degrees  (the  lowest  temperature  reached  being  only 
about  10°  C.)  was  essentially  the  same  as  that  noted  with  steer  E,  which 
was  subjected  to  a  difference  in  temperature  of  17  degrees  (the  lowest  tem¬ 
perature  being  about  5°  or  6°  C.).  Such  meager  data  do  not  permit  of 
drawing  many  conclusions,  and  it  is  probable  that  no  definite  mathematical 
relationship  can  be  established,  such  as  has  been  suggested  frequently  in 
the  literature,  i.  e.,  that  each  degree  fall  in  temperature  results  in  a  certain 
definite  (percentage)  rise®  in  metabolism. 

Pronounced  temperature  differences  did  not  exist  when  the  animals  were 
on  alfalfa  rations,  either  at  the  maintenance  or  submaintenance  level  of 
nutrition,  as  the  season  was  too  far  advanced  for  low  temperatures.  During 
maintenance  feeding  with  timothy  hay,  however,  two  experiments  with  steer 
E  are  available,  one  in  December  and  one  in  February,  for  a  study  of  the 
effect  of  low  and  high  temperatures.  In  these  two  experiments,  the  influence 
of  the  environmental  temperature  is  entirely  different  from  that  when  the 
steer  is  on  submaintenance  rations.  In  the  December  experiment  the  aver¬ 
age  chamber  temperature  was  22.3°  C.  and  in  the  February  experiment  it 
varied  from  3.6°  to  9.6°  C.,  being  on  the  average  about  6°  C.  The  differ¬ 
ence  in  temperature  was  thus  essentially  16°.  On  the  two  feed  days,  when 
7  kg.  of  timothy  hay  were  eaten  daily,  the  heat-production  per  500  kg.  of 
body -weight  was  16,000  and  15,600  calories  at  the  high  temperature  and 
15,300  and  15,600  calories  at  the  low  temperature.  In  other  words,  there 
was  essentially  no  difference  in  the  metabolism,  except  for  a  slightly  lower 
value  on  the  first  of  the  low  temperature  days.  On  the  first  day  of  fasting 
the  metabolism  at  the  high  temperature  was  12,300  calories  as  compared 
with  12,500  calories  at  the  low  temperature,  there  being  an  inappreciable 
increase  on  the  cold  day.  On  the  second  day  of  fasting  the  metabolism  was 
11,000  calories  as  compared  with  11,500  calories,  the  increase  being  5  per 
cent  at  the  low  temperature.  On  the  basis  of  the  heat-production  per  square 
meter  of  body-surface,  the  increase  was  70  calories  or  4  per  cent  on  the 
second  fasting  day.  Thus,  although  with  the  low  environmental  temperature 
there  is  seemingly  an  increase  in  the  heat-production  on  the  second  fasting 
day,  the  heat-production  on  the  two  food  days  is  practically  constant  regard¬ 
less  of  the  temperature,  or  in  one  instance  is  slightly  lower  at  the  low 
temperature.  One  may  therefore  conclude  that  the  difference  in  temperature 
has  practically  no  effect  upon  the  metabolism  when  the  steer  is  on  a  main¬ 
tenance  ration  of  timothy  hay.  It  is  somewhat  surprising  that  the  difference 
is  not  greater  on  the  second  day  of  fasting  than  was  actually  found.  From 
the  evidence  in  the  submaintenance  experiments,  where  the  lower  nutritive 
plane  renders  the  animal  seemingly  more  susceptible  to  the  environmental 
temperature,  so  that  there  is  a  demand  for  a  greater  heat-production  at  the 
lower  temperature,  one  would  have  expected  in  the  fasts  following  main¬ 
tenance  feeding  a  greater  heat-production  than  is  actually  recorded  on  the 
second  day  of  fasting  at  the  low  environmental  temperature. 

The  conclusion  drawn  from  these  data  that  a  low  environmental  tempera¬ 
ture  frequently  has  no  influence  upon  the  metabolism  is  fully  in  line  with 


“  Recently,  Capstick  and  Wood  (Journ.  Agric.  Sci.,  1922,  12,  p.  257)  found  with  swine  that  as 
the  environmental  temperature  decreased  below  the  critical  temperature  (21°  C.),  the  heat  loss 
increased  at  the  rate  of  about  4  per  cent  per  degree. 


202 


METABOLISM  OF  THE  FASTING  STEER 


the  findings  in  the  excellent  research  of  Magee,  who  studied  the  influence 
of  variations  in  the  external  temperature  upon  the  energy  exchange  of  the 
goat.0  Magee  found  that  between  13°  and  21°  C.  the  metabolism  is  essen¬ 
tially  constant.  Below  13°  C.  it  rises  only  slightly,  but  as  the  temperature 
passes  above  21°  C.  a  pronounced  gradual  increase  in  the  metabolism  is 
observed. 


Influence  of  Lying  and  Standing 

The  computation  of  the  heat-production  per  500  kg.  of  body-weight  and 
per  square  meter  of  body-surface  in  these  4-day  experiments  represents  an 
attempt  to  equalize  the  differences  in  the  body-size  of  the  animals  so  that 
the  values  for  the  different  days  of  each  experiment,  and  particularly  the 
values  for  the  different  animals,  may  be  compared  with  each  other.  A  still 
further  attempt  to  reduce  the  values  to  a  more  comparable  basis  would  be 
to  compute  the  heat-production  on  the  basis  of  uniformity  in  standing  and 
lying.* 6  Several  methods  of  making  this  computation  have  been  proposed, 
all  of  them  based  upon  too  few  experimental  data.  Our  own  observations 
on  the  difference  in  metabolism  in  the  lying  as  compared  with  the  standing 
position,  although  extensive,  are  not  sufficiently  extensive  to  be  fully  con¬ 
vincing.  The  information  secured  in  our  earlier  experiments  was  contami¬ 
nated  by  irregularity  in  the  movements  of  the  animal,  the  uncertainty  as 
to  when  the  animal  would  lie  down  or  stand  up,  and  the  inclusion  in  the 
lying  period  or  in  the  standing  period  of  the  effort  of  getting  down  or  of 
rising.  Since  the  conclusion  of  the  fasting  experiments  with  our  four  steers, 
however,  we  have  been  able  to  obtain  some  clear-cut  comparisons  of  the 
metabolism  during  standing  and  lying,  in  experiments  in  which  the  effort  of 
changing  from  one  position  to  the  other  has  been  ruled  out.  In  many  of 
these  experiments  we  observed  that  the  difference  in  position  resulted  in  a 
difference  of  from  20  to  30  per  cent  in  the  metabolism  on  days  with  feed, 
but  that  there  was  a  tendency  for  this  difference  to  diminish  during  fasting 
and  practically  to  disappear  after  the  second  or  third  day  of  fasting.  In 
other  experiments,  a  difference  in  the  metabolism  of  as  much  as  20  per  cent 
due  to  difference  in  body  position  persisted  even  to  the  fourth  or  fifth  day 
of  fasting,  although  there  were  occasionally  8-hour  periods  when  the  differ¬ 
ence  almost  disappeared.  It  seems  highly  probable  that  the  correction  for 
the  difference  in  position  is  somewhat  greater  than  that  reported  by  Forbes, 
Fries,  and  Kriss0  (see  p.  211).  Pending  further  information  on  this  point, 
however,  the  values  in  Table  53  for  the  24-hour  heat-production  during  the 
series  of  continuous  4-day  experiments  have  not  been  corrected  to  a  standard 
day  of  12  hours  standing  and  12  hours  lying. 

It  is  obvious  that  these  experiments,  by  their  very  nature,  represent  that 
period  of  an  animal's  existence  when  the  greatest  influence  of  the  activity 
of  standing  and  lying  is  to  be  found,  comprising  as  they  do  two  days  on 
feed  and  two  days  of  fasting.  Undoubtedly,  the  heat  values  would  be  some¬ 
what  lower  had  they  been  determined  exclusively  when  the  animal  was 

°  Magee,  Journ.  Agric.  Sci.,  1924,  14,  p.  506. 

6  Fries  and  Kriss,  Am.  Journ.  Physiol.,  1924,  71,  p.  60. 

e  Ibid.;  Forbes  and  Kriss,  Journ.  Agric.  Research,  1925,  31,  p.  1085. 


THE  BASAL  METABOLISM  OF  STEERS 


203 


lying.  Differences  in  muscular  activity  necessarily  occur,  however,  during 
a  24-hour  day,  especially  when  the  animals  are  searching  for  and  expecting 
food.  Such  activity  has  been  noted  in  the  records  of  the  number  of  hours 
spent  in  standing  and  lying  during  the  day,  and,  in  addition,  a  relative 
estimate  of  the  degree  of  activity  from  day  to  day  has  been  obtained  from 
the  kymograph  records.  These  records  show  that  in  general  the  activity 
was  not  very  great.  Assessing  the  degree  of  activity  as  indicated  on  the 
kymograph  records  on  the  crude  basis  of  minimum  (activity  I),  moderate 
(activity  II),  and  excessive  (activity  III)  activity,  we  would  say  that  in 
many  instances  activity  II  occurred  on  the  two  feed  days.  This  activity  is 
to  be  expected,  since  the  animals  were  eating,  digesting  their  feed,  and 
ruminating.  The  activity  on  the  two  fasting  days,  however,  was  usually 
somewhat  lower  than  on  the  two  feed  days-  Undoubtedly,  therefore,  the 
metabolism  on  the  first  two  days  with  feed  was  influenced  by  a  greater 
degree  of  stall  activity  than  the  metabolism  on  the  two  fasting  days.  Only 
when  the  animal  is  lying  is  the  muscular  activity  reduced  to  a  minimum. 
Indeed,  one  might  argue  that  if  the  animal  remained  absolutely  quiet  when 
standing,  the  metabolism  would  not  be  much  greater  than  when  lying.  This 
argument  is  in  part  borne  out  by  the  fact  that  as  the  fast  progresses  and  the 
animal  becomes  less  restive  while  standing,  the  difference  in  metabolism  due 
to  the  difference  in  body  position  tends  to  disappear.  (See  pp.  211  to  213.) 

The  Basal  Metabolism  of  Steers 

With  humans  it  is  argued  that  the  metabolism  measured  12  hours  after 
the  last  food  and  during  complete  muscular  repose  is  the  so-called  “basal 
metabolism"  and  that  for  comparative  purposes  it  is  permissible  to  com¬ 
pare  the  metabolism  of  one  individual  measured  under  these  conditions  with 
that  of  another  individual  measured  under  the  same  conditions.  Usually 
these  determinations  are  made  in  short  periods  and  are  supposed  to  repre¬ 
sent  the  minimum  metabolism.  The  metabolism  as  thus  determined  is  not, 
however,  the  irreducible  minimum,  for  undemutrition,  fasting,  and  sleep 
may  result  in  an  even  lower  metabolism.  From  the  standpoint  of  physi¬ 
ology,  it  is  important  to  measure  the  metabolism  of  various  living  organisms 
under  as  nearly  as  possible  constant  conditions,  in  order  to  have  a  suit¬ 
able  basis  for  the  comparison  of  different  individuals  of  the  same  and 
different  species. 

It  is  impossible  to  secure  complete  muscular  repose  with  ruminants,  for 
they  are  not  cooperative.  They  can  be  forced  to  stand  by  hitching  a  chain 
under  the  neck,  but  this  procedure  is  ineffective  after  several  hours,  as  they 
become  very  restless  and  irritable  under  prolonged  restriction.  They  will 
not  remain  in  the  lying  position  for  any  definite  length  of  time,  and  even 
when  they  are  lying  there  may  be  more  or  less  movement  of  the  body  and 
particularly  the  head.  It  would  be  ideal  to  measure  the  basal  metabolism 
of  ruminants  only  when  they  are  in  the  lying  position  and  quiet.  This  is 
usually  impracticable,  however,  and  the  metabolism  must  be  measured 
under  the  conditions  of  stall  activity,  in  which  the  animal  has  freedom  to 
rise  or  lie  down  at  will  and  to  perform  those  minor  muscular  movements 
permitted  by  the  rather  narrow  confines  of  the  stall,  though  restrained  by 


204 


METABOLISM  OF  THE  FASTING  STEER 


the  usual  stanchion.  The  sum  total  of  such  activities  is  reasonably  uniform 
from  day  to  day,  however,  as  is  strikingly  shown  in  the  continuous  4-day 
respiration  experiments  with  steers  E  and  F,  in  which  it  was  noted  that 
during  the  two  days  on  feed  the  total  24-hour  metabolism  was  almost  always 
the  same  on  any  two  succeeding  days. 

With  humans  and  carnivorous  animals  the  food  in  the  intestinal  tract  is 
fairly  rapidly  absorbed.  Immediately  after  the  ingestion  of  food  there  is  a 
rise  in  the  metabolism,  but  if  no  more  food  is  taken,  the  metabolism  gradu¬ 
ally  decreases  and  after  12  hours  a  plateau  is  reached  which  persists  prob¬ 
ably  for  12  or  more  hours,  during  which  time  there  is  only  an  insignificant 
alteration  in  the  metabolism.  Further  abstinence  from  food  results  in  a 
lowered  metabolism,  and  with  prolonged  fasting  the  metabolism  falls  off 
appreciably.  In  the  case  of  large  ruminants  there  are  large  masses  of  feed 
residues  in  the  alimentary  tract,  which  are  absorbed  only  slowly,  and  even 
after  food  is  withheld,  this  intestinal  content  may  contribute  to  the  metabo¬ 
lism  of  the  animal  for  some  time  by  furnishing  energy  from  material  either 
directly  absorbed  or  elaborated  by  fermentative  processes. 

Prior  to  our  study  of  undernutrition  in  steers,  few  respiration  experiments 
had  been  made  with  large  ruminants  in  which  feed  was  withheld  for  any 
length  of  time.  In  our  research  on  undernutrition,  the  metabolism  of  all  of 
the  steers  was  measured  for  comparative  purposes  24  hours  after  the  last 
food.  In  a  few  instances  in  1919,  measurements  were  made  50  or  more 
hours  after  food.®  It  was  early  recognized  that  although  the  digestion  of 
ruminants  has  by  no  means  completely  ceased  24  hours  after  the  last  feed, 
the  active  peak  of  digestion  has  passed.  Recent  determinations  of  the 
methane  production  of  cattle  in  Armsby’s  laboratory6  indicate  that  even 
during  the  second  24  hours  of  fasting  the  methane  production  is  relatively 
high  and,  though  it  falls  off  rapidly  during  the  first  three  days  after  feed, 
it  is  not  until  the  sixth  or  seventh  day  of  fasting  that  the  production  is  as 
low  as  2  or  3  gm.  per  day.  Without  doubt  the  methane  production  is  a  fair 
index  of  the  total  digestive  fermentation,  but  it  is  questionable  whether 
digestive  activity  as  such  has  not  essentially  ceased  even  before  the  great 
decrease  in  methane  production  takes  place. 

Although  the  stall  confinement  of  cattle  during  respiration  experiments 
makes  the  degree  of  muscular  activity  during  any  comparative  series  of 
metabolism  measurements,  especially  during  24-hour  periods  of  measure¬ 
ment,  more  or  less  uniform,  it  is  almost  impossible  to  secure  a  sharply 
defined  post-absorptive  state  in  the  ruminant.  Experimental  study  is  there¬ 
fore  necessary  to  determine  whether  a  fairly  definite  plateau  of  metabolism 
is  reached  after  the  peak  of  digestive  activity  has  passed,  corresponding  to 
that  noted  with  humans  12  hours  after  the  ingestion  of  food. 

Incidence  of  Plateau  in  Metabolism  of  Steers  after  Cessation  of  Active  Digestion 

In  our  series  of  long  fasts  (see  Tables  48  to  50,  pp.  173  to  178)  it  wad 
pointed  out  that  the  heat-production,  expressed  on  any  of  the  usual  three 
bases  of  computation,  decreases  rapidly  on  the  second  day  of  fasting,  that 
is,  the  period  beginning  42  to  56  hours  after  the  last  food.  There  is  fre- 


“  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  Table  55,  p.  210. 
b  Braman,  Journ.  Biol.  Chem.,  1924,  60,  p.  85. 


THE  BASAL  METABOLISM  ‘  OF  STEERS 


205 


quently  a  further  decrease  on  the  third  day.  An  examination  of  the  figures 
in  Table  49  (p.  176),  leaving  out  of  consideration  the  submaintenance 
experiments  in  March  1924,  with  steers  C  and  D,  and  the  submaintenance 
experiments  with  steers  E  and  F,  shows  that  in  12  experiments  with  steers 
C  and  D  approximately  a  plateau  in  metabolism  was  reached  on  the  second 
day  in  4  cases,  on  the  third  day  in  6  cases,  and  on  the  fourth  day  in  only 
2  cases.  Hence  it  would  seem  as  if  in  general  on  the  third  day,  that  is, 
during  the  24-hour  period  beginning  between  65  and  80  hours  after  food,  a 
fairly  uniform  metabolism  would  be  found,  which  would  not  be  rapidly 
altered  during  the  following  24  or  48  hours,  although  the  tendency  for  a 
continuous  decrease  in  metabolism  with  prolonged  fasting  is  obvious.  It 
should  be  borne  in  mind,  however,  that  the  data  given  in  Table  49  were 
secured  from  only  three  or  four  half-hour  periods  of  measurement,  usually 
in  the  forenoon,  and  in  at  least  two  cases  the  animals  had  just  come  in 
from  pasture.  In  the  other  cases,  they  were  presumably  at  a  maintenance 
level  of  nutrition,  but  since  their  body-weights  were  somewhat  different  in 
the  different  experiments,  they  were  not  necessarily  in  the  same  state  of 
nutrition  in  all  experiments.  Furthermore,  the  metabolism  of  steer  D,  on 
the  whole,  was  higher  than  that  of  steer  C,  in  large  part  accounted  for  by 
the  fact  that  steer  D  was  almost  invariably  somewhat  more  restless. 

In  the  continuous  3-day  experiments  with  steers  C  and  D  (see  Table  52, 
p.  186)  the  average  heat-production  of  steer  C  per  500  kg.  of  body-weight 
per  24  hours  was  practically  uniform  on  the  three  successive  fasting  days, 
being  8,100,  8,000,  and  7,900  calories,  respectively.  The  first  value  repre¬ 
sents  a  period  between  24  and  48  hours  after  food,  or  the  period  beginning 
24  hours  after  the  last  food.  This  period  is  essentially  the  same  as  that 
represented  by  the  first  day  of  fasting  in  the  fasts  of  5  to  14  days  (see 
Table  49),  but  the  value  of  8,100  calories  is  measurably  lower  than  the 
average  value  found  with  steer  C  in  the  longer  fasts.  The  same  may  be 
said  with  regard  to  steer  D.  His  heat-production  on  the  three  successive 
days  was  9,300,  9,200,  and  9,200  calories,  i.  e.,  perceptibly  lower  than  all 
except  one  value  found  on  the  first  day  in  the  long  fasts,  namely,  8,500 
calories  in  the  fast  in  April  1922.  The  subsequent  values  in  the  April  fast, 
however,  are  also  lower  than  the  values  found  in  the  other  long  fasts.  A 
possible  explanation  of  this  low  value  of  8,500  calories  may  be  the  pos¬ 
sibility  of  error  in  the  respiratory  quotient,  which  was  found  to  be  0.97 
on  this  day,  32  hours  after  the  last  food.  This  was  one  of  the  first  deter¬ 
minations  of  the  respiratory  quotient  made  with  the  new  gas-analysis 
apparatus  and,  judged  from  other  measurements  made  at  approximately 
the  same  time  after  food,  this  value  is  distinctly  high.  If  the  quotient  were 
lower,  the  value  for  the  heat-production  would  be  increased  somewhat,  pos¬ 
sibly  even  to  exceed  the  9,300  calories  noted  in  the  fast  in  May  1924. 
Another,  and  perhaps  more  logical,  explanation  of  this  low  value  in  the  fast 
of  April  1922,  inasmuch  as  it  would  at  the  same  time  account  for  the  low 
values  on  the  three  subsequent  days,  is  that  at  the  time  of  the  fast  in 
April  1922  steer  D  was  distinctly  in  an  undernourished  condition.  He  had 
been  through  two  fasts  during  the  winter,  a  10-day  fast  three  months 
before,  and  actually  weighed  621  kg.  at  the  beginning  of  the  fast  in  April 
1922,  as  compared  with  664  kg.  on  May  14,  1924. 


206 


METABOLISM  OF  THE  FASTING  STEER 


Judging  from  the  four  continuous  3-day  fasting  experiments  in  1924,  if 
one  begins  the  experiment  24  hours  after  the  last  food,  and  the  previous 
ration  has  been  a  maintenance  ration,  the  metabolism  per  500  kg.  of  body- 
weight  on  3  successive  days  is  essentially  the  same.  Thus,  one  would  be 
justified  in  saying  that  a  post-absorptive  condition,  or  essentially  a  post- 
absorptive  condition,  was  obtained  with  the  steer  on  a  maintenance  ration 
of  hay  alone  in  a  period  beginning  24  hours  after  food  was  withheld,  in 
other  words,  a  period  twice  as  long  as  that  ordinarily  assumed  for  man. 
Judging  from  the  longer  fasts,  however,  the  plateau  in  metabolism  occurs 
on  the  second  or  even  the  third  day,  rather  than  on  the  first  day,  i.  e.,  24 
hours  after  the  last  food.  A  strict  comparison  of  the  data  in  these  two 
series  of  fasts  is  complicated,  however,  by  the  fact  that  in  one  series  the 
animals  were  measured  while  standing  and  for  only  three  or  four  half-hour 
periods,  and  in  the  other  series  they  were  allowed  to  lie  or  stand  at  will  and 
the  periods  of  measurement  were  8  hours  long.  Therefore,  direct  compari¬ 
sons,  without  correcting  for  these  differences  of  conditions,  can  not  be  made. 

The  conclusion  as  to  the  incidence  of  a  plateau  in  metabolism  following 
the  cessation  of  active  digestion  would  seem  to  be  better  founded  upon 
24-hour  experiments  than  upon  short  experiments  of  about  2  hours.  Further 
evidence  on  this  point  is  available  in  the  experiments  made  on  steers  E  and 
F  from  December  1924  to  May  1925.  In  these  experiments  the  metabolism 
was  measured  in  8-hour  periods  during  two  days  of  fasting  following  two 
days  on  feed,  or  during  four  days  inside  the  respiration  chamber.  From  an 
inspection  of  the  8-hour  values  we  find  that  with  steer  E,  in  December 
1924,  a  plateau  in  metabolism  is  reached  in  approximately  16  hours  after 
the  last  feed.  The  time  when  the  plateau  in  metabolism  occurred  in  these 
4-day  experiments  is  recorded  in  Table  54,  which  shows  that  in  general  the 
plateau  begins  24  hours  or  later  after  the  last  food  has  been  consumed.  In 
the  submaintenance  experiments  it  occurs  in  most  cases  somewhat  later. 
This  is  strikingly  at  variance  with  what  one  would  expect,  for  one  would 
think  that  with  the  smaller  intestinal  content  the  effect  of  the  previously 
ingested  feed  would  pass  off  more  rapidly  and  the  plateau,  instead  of  being 
delayed,  would  be  more  quickly  reached.  It  was  thought  that  striking 
changes  in  temperature  might  possibly  have  an  influence  upon  the  time  when 
the  plateau  appeared.  An  inspection  of  the  average  chamber  temperatures 
recorded  in  Table  54,  however,  shows  that  environmental  temperature  is 
practically  without  significance  in  this  respect.  From  the  series  of  con¬ 
tinuous  3-day  fasting  experiments  inside  the  chamber,  in  which  the  animals 
had  previously  been  upon  a  maintenance  level,  it  was  inferred  that  24  hours 
after  the  last  food  was  given  a  plateau  in  the  metabolism  of  the  steers  was 
reached  which  might  be  considered  as  comparable  to  the  post-absorptive 
metabolism  of  man.  This  is  in  general  confirmed  by  the  4-day  experiments 
at  the  maintenance  level,  as  seen  from  Table  54,  but  on  the  submaintenance 
level  this  period  is  evidently  somewhat  delayed. 

The  Metabolic  Plateau  of  the  Same  Animal  when  Fasting  Under  Different 

Conditions 

In  the  fasts  of  5  to  14  days  it  was  pointed  out  that  a  level  in  the  fasting 
metabolism  might  not  occur  until  the  second  or  even  the  third  or  fourth  day 


THE  BASAL  METABOLISM  OF  STEERS 


207 


of  fasting.  Another  point  to  be  considered  is  that  the  metabolism  was 
rarely  the  same  with  the  same  animal  for  the  first  day  or  even  for  subsequent 
days  of  these  different  fasts,  since  the  prefasting  conditions  were  different. 
Thus,  excluding  the  experiment  at  the  submaintenance  level,  the  average 
24-hour  heat-production  of  steer  C  per  500  kg.  of  body-weight  during  four 
half-hour  periods  in  the  standing  position  ranged  from  8,800  to  9,800  calories 
on  the  first  day  of  fasting,  i.  e.,  22  to  32  hours  after  food.  With  steer  D  the 
differences  were  even  greater,  the  metabolism  ranging  from  8,500  to  12,000 
calories.  Similar  variations  are  found  on  the  subsequent  days.  During  the 
first  few  hours  following  the  time  when  the  first  feed  is  withheld,  i.  e.,  about 
12  hours  after  the  last  feed,  one  expects  considerable  variability  in  metabo¬ 
lism,  depending  upon  the  nature  and  amount  of  the  previous  feed-level. 
Whether  the  plateau  indicating  approximately  basal  metabolism  will  be  at 
the  same  level  in  all  experiments  when  the  animal  is  subsisting  upon  a 
maintenance  ration  becomes  a  vital  point  at  issue.  In  the  different  fasts 
of  5  to  14  days  with  steers  C  and  D,  excepting  those  in  March  1924,  the 
level  of  the  plateau  did  vary,  although  this  may  have  been  due  to  the  fact 
that  the  rations  preceding  the  fasts,  which  were  supposedly  maintenance, 
consisted  of  hay  in  some  cases  and  grass  in  others. 


Table  54.- — Incidence  of  'plateau  in  metabolism  after  cessation  of  active  digestion, 
in  4-day  respiration  experiments  with  steers  E  and  F 


Steer  and 
date  of 
experiment 

Feed-level 

Time  after  food 
when  plateau  in 
metabolism  seems 
to  appear 

Average 

chamber 

temperature 

1924  to  1925 

Steer  E: 

hrs. 

°C. 

Maintenance . 

16 

22 

Do . 

24 

6 

Do . 

24 

22 

April . 

Do . 

24 

22 

January . 

Submaintenance .... 

40 

22 

Do . 

32 

6 

May . 

Do . 

32 

22 

Steer  F: 

Dprpmhpr . 

M  aintenance . 

16 

22 

Do . 

32 

22 

April . 

Do . 

24 

22 

January . 

Submaintenance . 

32 

22 

Do . . 

32 

10 

May . 

Do . 

24 

22 

The  4-day  experiments  with  steers  E  and  F  in  1925  furnish  additional 
evidence  on  this  point.  Thus,  the  data  for  the  4-day  experiments  with 
maintenance  rations  indicate  that  in  the  8-hour  periods  of  measurement 
the  level  of  the  plateau  may  range  from  approximately  8,700  calories  per 
24  hours  to  6,750  calories  in  the  case  of  steer  E,  and  from  8,700  to  7,650 
calories  in  the  case  of  steer  F.“  In  other  words,  the  so-called  “basal  metabo- 

•  These  values  are  calculated  from  the  8-hour  periods  of  measurement  and  do  not  appear  in 
Table  53. 


208 


METABOLISM  OF  THE  FASTING  STEER 


lism,  when  once  attained  after  withholding  of  food,  is  seemingly  not  con¬ 
stant  with  the  same  animal,  even  if  he  has  previously  been  upon  a  main¬ 
tenance  feed-level.  If  these  experiments  at  the  maintenance  level  are 
subdivided,  however,  according  to  whether  the  animal  had  been  receiving 
timothy  or  alfalfa  hay,  it  is  seen  that  the  higher  values  occur  following  the 
ration  of  timothy  hay  and  the  lower  values  following  the  ration  of  alfalfa 
hay. 

A  submaintenance  ration  has  been  shown  to  lower  the  level  of  the  fasting 
metabolism  markedly.  The  most  important  evidence  on  this  point  is 
brought  out  by  the  fasts  with  steers  C  and  D  in  March  1924,  at  the  sub¬ 
maintenance  level,  when  extraordinarily  low  values  for  both  animals  were 
found.  Similarly  with  the  younger  steers,  E  and  F,  at  a  submaintenance 
level  the  heat-production  per  500  kg.  of  body-weight  per  24  hours  on  the 
first  day  of  fasting  in  February  1924  was,  respectively,  10,900  and  10,300 
calories.  These  same  animals,  when  fasting  at  a  maintenance  level  in  April 
1924,  that  is,  about  six  weeks  after  the  submaintenance  experiments  in 
February  1924,  had  a  fairly  constant  metabolism  during  three  days,  steer 
E  of  13,600  calories  and  steer  F  of  12,700  calories.  In  other  words,  as  was 
the  case  with  steers  C  and  D,  the  metabolism  was  materially  lower  on  sub¬ 
maintenance  rations  and  the  two  conditions  represented  plateaus  at  differ¬ 
ent  levels.  The  4-day  experiments  with  steers  E  and  F  on  submaintenance 
rations  furthermore  show  that  although  the  fasting  metabolism  is  on  a 
lower  level  than  it  was  following  maintenance  feeding,  the  metabolic  level 
is  higher  following  the  submaintenance  ration  of  timothy  hay  than  it  is 
following  the  submaintenance  ration  of  alfalfa  hay. 

Conclusions  Regarding  the  Incidence  and  the  Level  of  the  Plateau  in  Metabolism 

of  Steers 

On  the  basis  of  all  the  data  available,  one  can  conclude  that  vnth  the 
steer  on  essentially  a  maintenance  ration  a  plateau  of  fairly  constant 
metabolism  begins  in  many  instances  24  hours  after  the  last  food,  depending 
somewhat  upon  the  amount  and  nature  of  the  food,  and  that  this  level  will 
remain  essentially  constant  for  three  successive  days.  In  some  instances, 
32  hours  are  required,  singularly  enough  especially  in  those  cases  where  the 
steers  were  upon  submaintenance  rations.  In  all  probability  at  the  end  of 
48  hours  the  animal  is  in  a  condition  which  is  comparable,  at  least,  with  the 
so-called  post-absorptive  state  in  humans.  It  is  difficult  to  give  an  exact 
percentage  valuation  to  the  difference  between  the  probable  level  of  metabo¬ 
lism  24  hours  after  food  as  compared  with  that  48  hours  after  food,  but 
undoubtedly  the  peak  of  digestion  has  been  passed  24  hours  after  the  last 
food  and  the  measurements  of  metabolism  at  this  time  may  certainly  be 
used  for  comparative  purposes.  Whether  it  is  justifiable  to  assume  that 
with  the  average  ruminant  the  metabolism  determined  24  hours  after  the 
last  food  represents  the  basal  metabolism  is  highly  doubtful.  In  general, 
from  our  evidence  one  would  say  that  the  metabolism  beginning  48  hours 
after  food  is  withheld  would  be  less  liable  to  fluctuation  during  the  fol¬ 
lowing  48  hours  than  perhaps  at  any  other  point  in  the  course  of  the 
metabolism. 


THE  BASAL  METABOLISM  OF  STEERS 


209 


According  to  the  evidence  secured  in  the  long  fasts  with  steers  C  and  D 
and  in  the  4-day  experiments  with  steers  E  and  F,  the  level  in  the  plateau 
of  metabolism  will  vary  with  different  seasons  of  the  year  and  as  a  result 
of  changes  in  the  quantity  and  character  of  the  rations. 

Since  with  steers  it  is  impossible  to  insure  complete  muscular  repose,  since 
it  is  difficult  to  secure  complete  cessation  of  digestive  activity,  and  further¬ 
more,  since  the  digestive  activity  of  ruminants  is  relatively  very  great  com¬ 
pared  with  that  of  humans,  it  is  debatable  whether  any  attempt  to  secure 
the  equivalent  of  basal  conditions  in  man  is  necessarily  advisable. 

In  all  the  foregoing  discussion  the  conclusions  have  been  based  chiefly 
upon  the  heat-production  per  500  kg.  of  body-weight  per  24  hours.  But 
since  the  surface  area  is  a  function  of  the  body-weight,  the  conclusions 
may  also  be  based,  without  the  slightest  change  in  phraseology  other  than 
that  of  numbers,  upon  the  heat  as  computed  per  square  meter  of  body- 
surface  per  24  hours. 

Computation  of  the  Fasting  Katabolism  of  Steers  from  Experiments  on  Two 

Different  Feed-levels 

The  exact  determination  of  the  period  of  time  following  food  intake  when 
the  metabolism  should  be  measured  for  purposes  either  of  comparing  the 
basal  metabolism  of  a  ruminant  with  his  metabolism  immediately  following 
the  ingestion  of  food  or  of  comparing  the  basal  metabolism  of  one  ruminant 
with  that  of  other  ruminants,  other  animals,  or,  indeed,  man,  is  a  matter  of 
considerable  importance.  With  man  the  metabolism  12  hours  after  the  last 
meal  is  commonly  used  as  the  basis  for  the  study  of  the  influence  of  subse¬ 
quently  superimposed  factors,  such  as  food,  muscular  activity,  and  a  warm 
or  cold  environmental  temperature.  To  study  the  energy  value  of  various 
cattle  feeds  it  is  also  highly  desirable  to  be  able  to  superimpose  the  effect 
of  the  feed  upon  a  metabolism  determined  under  basal  conditions. 

Formerly  it  was  considered  that  the  basal  or  fasting  katabolism  could 
be  computed  by  the  simple  process  of  measuring  the  metabolism  of  an 
animal  when  consuming  daily  a  given  amount  of  food,  and  subsequently 
determining  the  metabolism  of  the  same  animal  when  consuming  approxi¬ 
mately  one-half  of  this  amount  of  food.  The  difference  in  metabolism  at 
the  two  feed-levels  was  ascribed  to  the  difference  in  the  amount  of  the 
ration,  and  the  fasting  katabolism  was  computed  as  a  linear  function  of 
this  difference.  This  method  was  first  proposed  and  applied  by  Professor 
Armsby  many  years  ago,®  and  was  in  large  part  based  on  his  own  conviction 
that  the  actual  fasting  katabolism  of  ruminants  could  not  be  determined 
definitely.  In  the  spring  of  1919,  Professor  Armsby  visited  the  laboratory 
at  Durham,  New  Hampshire,  and  having  seen  the  excellent  manner  in 
which  our  large  steers  had  withstood  undemutrition  for  long  periods  of 
time  and  having  learned  that  we  had  made  all  of  our  respiration  experi¬ 
ments  at  least  24  hours  after  the  last  food,  stated  that  he  believed  more 
prolonged  fasting  would  be  feasible  and  suggested  that  we  continue  our 
fasting  period  to  the  fiftieth  hour.  It  is  significant  that  a  fasting  experiment 
prolonged  to  50  hours  was  made  on  May  5-6,  1919,  i.  e.,  at  the  time  of  his 


°  Armsby,  Principles  of  Animal  Nutrition,  New  York,  1906,  2d  ed.,  p.  378. 


210 


METABOLISM  OF  THE  FASTING  STEER 


visit.  At  the  same  conference  Professor  Armsby  expressed  himself  as  being 
uncertain  whether  the  method  of  computing  the  fasting  katabolism  from 
two  different  feed-levels  was  as  sound  as  he  had  originally  believed.  This 
matter  was  touched  upon  in  our  report  on  undernutrition.® 

Our  experiments  in  which  the  fast  was  prolonged  for  52  hours  or  more 
show,  as  is  to  be  expected,  that  there  is  a  decrease  in  the  carbon-dioxide 
production,  due  to  the  fact  that  the  respiratory  quotient  and  the  total 
metabolism  gradually  decrease.  Even  in  cattle  the  after-effect  of  food 
apparently  disappears  rapidly,  and  the  condition  approximating  the  pre¬ 
requisite  for  basal  metabolism  measurements  with  man,  so  far  as  the 
question  of  food  ingestion  is  concerned,  is  attained  with  ruminants  not  far 
from  32  to  48  hours  after  food  is  withheld.  Prolonged  fasting  will  lower 
the  metabolism  still  further,  as  was  clearly  shown  with  the  man  who  fasted 
for  31  days6  and  as  is  shown  in  the  fasts  of  5  to  14  days  with  our  steers. 
But  for  the  specific  purpose  of  finding  an  approximate  base-line  for  cattle, 
to  which  the  influence  of  the  ingestion  of  food  may  be  referred,  and  to 
establish,  if  possible,  a  basal  katabolism  of  steers  for  comparison  with 
other  animals  and  humans,  we  obviously  may  not  deal  either  with  prolonged 
fasting  or  prolonged  submaintenance  feeding,  for  this  latter  factor  is  like¬ 
wise  shown  to  lower  the  metabolism  pronouncedly.  Indeed,  the  most  ardent 
advocates  of  the  surface-area  law  insist  that  normal  conditions  of  nutrition 
should  be  maintained.  A  critical  study  of  our  fasting  results  suggests  that 
with  animals  under  approximately  normal  conditions  of  nutrition  the  with¬ 
holding  of  food  for  32  hours  should  give,  so  far  as  the  influence  of  food  is 
concerned,  favorable  conditions  for  approximating  the  basal  level.  Even 
then,  as  is  seen  from  the  metabolism  measurements  during  the  fasts  of  5 
to  14  days,  large  differences  may  occur  in  different  experiments  with  the 
same  animal,  although  the  nutritive  condition,  ruling  out  of  such  compari¬ 
son  the  experiments  on  a  submaintenance  level,  may  not  be  pronouncedly 
different.  This  finding  is  in  common  with  that  not  infrequently  noted 
with  man,  and  speaks  for  an  absence  of  strict  uniformity  in  metabolism 
even  with  the  same  individual,  when  changes  in  age  are  ruled  out. 

The  object  of  this  report  is  not  primarily  to  study  the  effect  of  the  inges¬ 
tion  of  food  upon  metabolism  so  as  to  make  use  of  this  base-line  obtained 
32  to  48  hours  after  food,  but  it  is  pointed  out  here  that  the  results  suggest 
that  this  seems  to  be  a  logical  procedure.  From  the  standpoint  of  com¬ 
parative  physiology  it  is  important  to  compare  the  basal  metabolism  of  the 
steer  determined  under  these  conditions  with  that  noted  with  other  animals, 
particularly  man.  Two  decades  ago  there  was  an  attempt,  commonly  attrib¬ 
uted  to  Erwin  Voit,c  to  suggest  complete  uniformity  in  the  heat-production 
of  all  warm-blooded  animals  per  unit  of  surface  area.  At  that  time  almost 
no  attention  was  given  to  the  degree  of  muscular  activity,  a  factor  now 
known  to  be  of  great  importance.  The  question  of  the  presence  or  lack 

°  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  257.  We  wish  to  explain 
here  that  although  our  statement  in  our  earlier  publication  refers  solely  to  a  letter  received  from 
Professor  Armsby,  as  a  matter  of  fact  several  days’  intimate  conference  with  him  in  Boston  and  at 
Durham  was  the  basis  for  our  general  statement  of  Professor  Armsby’s  beliefs. 

1  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  203,  1915. 

*  E.  Voit,  Zeitschr.  f.  Biol.,  1901,  41,  p.  113. 


THE  BASAL  METABOLISM  OF  STEERS 


211 


of  food  in  the  stomach  was  also  not  seriously  considered.  The  effect  of 
environmental  temperature  was  only  incidentally  noted,  and  the  method 
for  computing  the  surface  area  of  the  various  species  of  animals  was  only 
in  its  earliest  stages  of  development.  Under  these  conditions,  however,  it 
was  stated  that  throughout  the  entire  animal  kingdom  the  heat-production 
was  seemingly  uniform,  amounting  to  approximately  1,000  calories  per 
square  meter  of  body-surface  per  24  hours,  when  the  animal  was  in  a 
normal  state  of  nutrition. 

In  1918,  Armsby,  Fries,  and  Braman®  published  a  comparison  of  the 
basal  katabolism  of  cattle  and  other  species,  in  which  they  pointed  out 
the  difficulties  of  measuring  or  computing  the  basal  katabolism  of  cattle. 
By  comparing  the  total  metabolism  on  two  different  amounts  of  the  same 
feed  and  noting  the  increment  in  the  heat-production  per  kilogram  of  dry 
matter  of  the  feed,  they  computed  indirectly  the  24-hour  basal  katabolism 
of  a  number  of  cattle.  Since  they  found  a  great  difference  in  the  heat- 
production  according  to  whether  the  animal  was  lying  or  standing,  they 
compute  their  basal  katabolism  data  upon  three  different  bases,  namely, 
that  the  animal  was  lying  for  24  hours,  standing  for  12  hours  and  lying 
for  12  hours,  and  standing  the  entire  24  hours.  On  the  basis  of  24  hours 
lying,  the  average  computed  basal  katabolism  of  their  cattle  was  964 
calories  per  square  meter  of  body-surface  per  24  hours.  In  determining 
the  surface  area  of  their  cattle  these  investigators  had  the  distinct  advan¬ 
tage  of  using  the  more  modern  formula  for  surface-area  measurements  as 
suggested  by  Moulton,* 6  but  they  had  to  determine  the  basal  katabolism  by 
the  method  of  computation.  This  value  of  964  calories  they  compare  with 
the  value  of  935  calories  found  with  men,  886  calories  found  with  women 
in  complete  muscular  repose,  1,078  calories  with  hogs,  lying,  and  948 
calories  with  a  horse,  standing  quietly.  In  their  opinion  this  comparison 
confirms  the  conclusions  of  E.  Voit.° 

CORRECTION  OF  BASAL  KATABOLISM  TO  A  STANDARD  DAY  AS  TO  STANDING  AND  LYING 

The  Pennsylvania  investigators  computed  that  the  basal  katabolism  of 
their  cattle  per  square  meter  of  body-surface,  when  the  cattle  were  standing 
for  the  entire  24  hours,  was  1,365  calories  or  401  calories  greater  than  when 
the  animal  was  lying  24  hours.  The  increment  due  to  the  standing  position 
is  thus  41  per  cent.  It  is  perhaps  unfortunate  at  this  time  to  discuss  the 
results  of  the  Pennsylvania  Institute  of  Animal  Nutrition  since  Dr. 
Armsby’s  death,  for  evidently  an  extensive  revision  of  calculations  and 
factors  is  now  being  made.  If  the  discussion  is  confined,  however,  entirely 
to  their  own  published  data,  one  is  justified  in  pointing  out  several  signifi¬ 
cant  facts.  In  the  first  place,  the  difference  of  approximately  41  per  cent 
between  the  metabolism  in  the  lying  and  standing  positions  is,  in  accord¬ 
ance  with  the  latest  published  and  corrected  computations  from  the  Penn¬ 
sylvania  institute,  very  large,  for  the  more  recent  figures  of  Fries  and 
Kriss'1  would  imply  a  difference  of  approximately  9  per  cent.  The  standards 

°  Armsby,  Fries,  and  Braman,  Journ.  Agric.  Research,  1918,  13,  p.  43. 

6  Moulton,  Journ.  Biol.  Chem.,  1916,  24,  p.  299. 

*  E.  Voit,  Zeitschr.  f.  Biol.,  1901,  41,  p.  113. 

Fries  and  Kriss,  Am.  Journ.  Physiol.,  1924,  71,  p.  60. 


212 


METABOLISM  OF  THE  FASTING  STEER 


of  Fries  and  Kriss  are  derived  from  a  series  of  experiments  with  one  espe¬ 
cially  satisfactory  animal,  cow  874,  which  gave  off  4.9162  calories  per 
minute  while  standing  and  4.4771  calories  per  minute  while  lying.  The 
difference  is  0.4391  calorie,  which  represents  a  decrease  in  the  heat-produc¬ 
tion  with  a  change  in  body  position  from  standing  to  lying  of  about  9  per 
cent.  Our  own  data  regarding  the  difference  in  metabolism  in  the  two 
positions  are,  as  already  stated  (see  p.  202),  not  extensive  enough  to  permit 
of  drawing  definite  conclusions,  but  on  the  basis  of  our  results  it  seems 
highly  probable  that  the  correction  factor  might  in  general  be  nearer  20 
than  9  per  cent,  with  a  probable  influence  of  the  length  of  time  since  feed 
was  withheld. 

Since  this  percentage  correction  plays  an  important  role  in  the  computa¬ 
tion  of  the  basal  katabolism  of  cattle,  when  the  computation  is  made  on 
the  basis  of  24  hours  lying,  12  hours  standing  and  12  hours  lying,  or  24 
hours  standing,  it  can  be  seen  that  the  earlier  reported  values  for  the  basal 
metabolism  are  immediately  open  to  criticism.  Since  animals  for  the  most 
part  stand  approximately  12  out  of  the  24  hours,  the  correction  to  24  hours 
lying  upon  the  old  basis  (41  per  cent)  is  obviously  too  large,  possibly  30 
per  cent  too  large  on  the  basis  of  the  9  per  cent  difference  indicated  by  the 
recent  data  of  Fries  and  Kriss. 

M0llgaarda  has  based  a  recent  report  on  the  metabolism  of  cattle  in 
large  part  upon  the  method  of  calculation  devised  by  Professor  Armsby, 
but  he  does  not  make  the  correction  for  difference  in  body  position.  At 
the  time  of  closing  our  report  on  undernutrition  it  was  stated  that  we  had 
only  just  received  the  report  of  M0llgaard  with  regard  to  the  respiration 
experiments  in  his  laboratory  in  Copenhagen.  This  report  is,  unfortunately, 
printed  in  Danish,  although  some  of  the  table  headings  are  in  English  and 
there  is  a  short  summary  in  English.  We  have  therefore  been  considerably 
handicapped  in  analyzing  his  data,  and  it  is  more  than  likely  that  points 
raised  in  the  following  discussion  may  have  been  adequately  cared  for  by 
Professor  Mpllgaard,  whose  keenness  not  only  in  scientific  research  but 
in  the  presentation  of  his  results  is  well  known  by  all  who  have  come  in 
contact  with  him.  The  experiments  were  made  with  the  respiration  cham¬ 
ber  at  Copenhagen.  In  this  report  we  find  no  statement  as  to  the  environ¬ 
mental  temperature,  but  in  an  English  summary  of  his  work* * * 6  is  the  state¬ 
ment  that  all  of  his  respiration  experiments  were  made  at  an  environmental 
temperature  of  18°  C.  and  as  nearly  as  possible  the  same  temperature  was 
maintained  in  the  stable  (17.5°  to  18.5°  C.).  M0llgaard’s  results  do  not 
confirm  Armsby’s  conclusion  that  the  metabolizable  energy  of  a  single 
feedstuff  has  a  reasonably  constant  value.  M0llgaard's  treatment  of  the 
question  of  the  influence  of  lying  and  standing  is,  however,  of  especial 
interest,  although  we  have  to  differ  strongly  with  one  of  his  points  of  view 
in  this  respect.  He  concludes,  from  an  examination  of  his  metabolism 

“  M0llgaard,  Om  Naeringsvaerdien  af  Roer  og  Byg  til  Fedning  og  om  Naeringsatofforholdets 

Betydnmg  for  Fodermidlernea  Naeringavaerdi.  Beretning  111,  Fors0gslaboratoriet.  Copen¬ 

hagen,  1923,  159  pp. 

6  M0llgaard,  New  viewa  regarding  the  acientific  feeding  of  dairy-cattle.  Compt.  Rend.  d.  Tra- 
vaux  d.  Congrfea  Internat.  pour  l’filevage  d.  l’Eap&ce  Bovine  (The  Hague) :  Internat.  Cong. 
Rundveeteelt,  1923,  p.  272. 


THE  BASAL  METABOLISM  OF  STEERS 


213 


measurements  and  the  relative  times  that  the  animals  are  standing  and 
that  the  metabolism  in  the  standing  position  is  not  independent 
quantitatively  of  that  in  the  lying  position,  the  increase  in  metabolism 
when  the  animal  is  standing  being  compensated  by  a  corresponding  decrease 
when  it  is  lying  down.  “When  the  time  of  standing  and  the  metabolism 
is  computed  for  24  hours,  there  is  absolutely  no  correlation  of  long-time 
standing  to  high  values  of  heat-production  in  respiration  experiments  on 
constant  feed.”  As  a  result  of  these  experiments,  M0llgaard  decides  not  to 
correct  the  metabolism  to  a  uniform  day  of  standing  and  lying. 

Since  the  average  stall  experiments  indicate  that  animals  spend  not  far 
from  12  hours  standing  and  12  hours  lying  (although  rather  large  differ¬ 
ences  are  occasionally  observed),  the  importance  of  this  correction  is  not 
so  great  when  the  value  of  different  feeds  are  being  compared  as  it  is 
perhaps  in  the  theoretical  discussion  concerning  the  true  fasting  katabolism 
of  animals,  especially  when  this  corrected  value  is  to  be  compared  with 
the  measured  basal  metabolism  of  other  warm-blooded  animals,  particu¬ 
larly  man.  The  value  of  26.34  calories  per  hour  suggested  by  Fries  and 
Kriss  as  the  increase  due  to  standing  in  the  case  of  a  400-kg.  cow,  or  the 
computed  difference  of  9  per  cent,  has  the  disadvantage  of  being  deter¬ 
mined  upon  only  one  animal.  Another  difficulty  in  attempting  to  correct 
for  the  difference  in  body  position  is  the  fact  that  the  influence  of  the  effort 
of  getting  up  or  lying  down  is  frequently  included  in  the  comparative 
measurements.  Obviously  in  determining  the  rate  of  metabolism  in  most 
of  the  practical  problems,  such  effort  is  a  legitimate  part  of  the  day’s 
activity,  although  it  should  not  be  included  in  computing  the  basal 
katabolism. 

INHERENT  ERROR  IN  METHOD  OF  COMPUTING  THE  FASTING  KATABOLISM  FROM  EXPERIMENTS 

ON  TWO  DIFFERENT  FEED-LEVELS 

In  our  study  of  undernutrition  in  steers,  we  found  at  no  time  values  for 
the  heat-production  per  square  meter  of  body-surface  as  low  as  the  964 
calories  reported  by  Armsby,  although  the  metabolic  level  was  greatly 
lowered  as  a  result  of  the  submaintenance  regime.  Our  measurements  were, 
to  be  sure,  always  made  with  the  steer  in  the  standing  position,  and  if  the 
correction  of  9  per  cent  were  applied,  our  values  for  the  measured  heat- 
production  per  square  meter  of  body-surface  would  be  lowered  by  9  per 
cent,  to  bring  them  presumably  to  the  lying  basis.  With  our  submainte¬ 
nance  groups  of  steers,  with  which  the  lowest  values  were  found  between 
February  11  and  May  2,  the  average  heat-production  per  square  meter  of 
body-surface  was  not  far  from  1,460  calories  in  the  submaintenance  period.® 
If  this  value  were  reduced  by  9  per  cent  to  approximate  the  lying  condition, 
the  metabolism  would  be  about  1,330  calories  per  square  meter,  even  during 
this  prolonged  period  of  undernutrition.  Indeed,  if  a  20  per  cent  correction 
is  applied,  the  value  remains  about  1,200  calories.  In  the  fasting  experi¬ 
ments  here  reported  it  was  found  that  the  heat-production  per  square  meter 
of  body-surface,  measured  always  in  the  standing  position,  ranged,  for  the 


°  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  fig.  40,  p.  292. 


214 


METABOLISM  OF  THE  FASTING  STEER 


most  part,  around  1,700  calories  on  the  day  beginning  from  42  to  56  hours 
after  the  last  food,  except  in  the  case  of  undemutrition.  But  even  with 
undernutrition  a  value  of  1,600  or  1,700  calories  was  found  with  steers  E 
and  F.  If  these  values  were  to  be  lowered  by  approximately  9  per  cent, 
to  bring  them  to  the  lying  basis,  they  would  still  be  around  1,450  to  1,550 
calories,  agreeing  more  closely  with  the  value  of  1,330  calories  computed 
for  the  submaintenance  experiments. 

Additional  evidence  regarding  the  probable  basal  metabolism  of  steers 
is  available  in  the  experiments  made  between  50  and  53  hours  after  feeding 
with  several  of  -the  steers  used  in  our  earlier  submaintenance  study.0  The 
heat-production  per  square  meter  of  body-surface  per  24  hours  has  been 
computed  in  these  instances  from  the  carbon-dioxide  production,  an 
assumed  respiratory  quotient  of  0.76,  and  a  body-surface  calculated  from 
the  formula  S  —  W%  X  0.1081  (see  Fig.  8,  p.  155).  Application  of  the  9  per 
cent  correction,  to  reduce  the  values  to  the  basis  of  24  hours  lying,  results 
in  values  ranging  from  1,170  to  1,970,  averaging  about  1,550  calories. 

It  seems  improbable  that  the  metabolism  of  the  steer  42  to  56  hours  after 
food  should  not  be  approximating  the  basal  condition.  But  even  after  the 
most  prolonged  fasting  of  14  days  the  heat-production  was  about  1,400 
calories  per  square  meter  of  body-surface.  If  it  were  permissible  to  reduce 
this  by  9  per  cent  to  bring  it  to  a  basis  of  24  hours  lying,  the  heat-produc¬ 
tion  would  still  be  1,270  calories  at  the  end  of  this  long  period  of  fasting. 
Our  evidence,  therefore,  points  strongly  to  the  fact  that  the  basal  katab- 
olism  of  cattle  is  about  1,300  calories  per  square  meter  of  body-surface 
per  24  hours,  when  the  animal  is  lying  the  entire  time. 

In  a  recent  article,  Cochrane,  Fries,  and  Braman6  discuss  the  maintenance 
requirements  of  dry  cows  and  use  the  method  of  computing  the  fasting 
katabolism  by  comparison  of  the  effects  produced  by  different  amounts  of 
the  same  feed.  Computing  the  experiments  on  the  basis  of  12  hours  stand¬ 
ing  and  12  hours  lying,  they  present  values  for  the  fasting  katabolism  of 
3  of  their  cows.  If  the  surface  areas  of  these  cows  are  computed  from 
their  live  weights  by  means  of  the  curve  in  Fig.  8  (see  p.  155)  and  if  the 
reported  values  for  the  fasting  katabolism  are  divided  by  the  surface  areas, 
the  24-hour  heat-production  per  square  meter  of  body-surface  is  found  to 
be  857,  824,  and  827  calories,  or,  on  the  average,  836  calories  in  the  case 
of  cow  886,  1,123  calories  in  the  case  of  cow  874,  and  1,079  calories  in  the 
case  of  cow  887.  The  authors  have  commented  upon  the  differences  between 
the  values  for  the  fasting  katabolism,  stating  that  cow  886  was  extremely 
quiet,  spending  more  than  half  of  the  experimental  time  in  the  lying  posi¬ 
tion,  that  cow  874  spent  about  half  her  time  lying  quietly,  but  when  stand¬ 
ing  Was  much  more  restless,  and  that  cow  887  stood  the  greater  part  of  the 
time  and  was  more  or  less  restless,  even  when  lying.  These  experiments 
were  computed  on  the  basis  of  12  hours  standing  and  12  hours  lying.  If  the 
values  were  to  be  corrected  to  the  basis  of  24  hours  lying,  in  order  to  com¬ 
pare  them  with  the  basal  metabolism  of  man,  they  would  all  be  reduced  by 

°  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  Table  55,  p.  210. 

5  Cochrane,  Fries,  and  Braman,  Journ.  Agric.  Research,  1925,  31,  Table  XXII,  p.  1078. 


THE  BASAL  METABOLISM  OF  STEERS 


215 


approximately  4.5  per  cent.  The  average  heat-production  would  then  be 
798  calories  for  cow  886,  1,073  for  cow  874,  and  1,030  calories  for  cow  887. 
These  values  are  much  more  in  accord  with  those  computed  by  Armsby, 
Fries,  and  Braman  in  1918.  As  a  matter  of  fact,  the  average  heat-produc¬ 
tion  of  cows  886,  874,  and  887  would  be  967  as  compared  with  the  average 
value  for  their  group  of  animals  of  964  calories. 

These  values  are  so  at  variance  with  our  own  findings,  both  in  our  earlier 
study  of  undernutrition  and  in  this  present  study  of  fasting,  as  to  suggest 
that  a  serious  error  inherent  in  the  method  of  computing  the  fasting 
katabolism  accounts  for  their  low  results.  An  analysis  of  the  values  for 
the  actually  observed  heat-production  of  these  same  cows,  886,  874,  and 
887,  published  by  Braman®  in  1924,  one  year  previous  to  the  publication  of 
the  values  for  the  computed  fasting  katabolism  by  Cochrane,  Fries,  and 
Braman,  strengthens  us  in  our  conviction  that  the  method  of  computing 
the  fasting  katabolism  is  in  all  likelihood  at  fault. 

The  minimum  24-hour  heat-production  of  these  cows,  as  measured  in 
the  calorimeter,  was  6,061  calories.  This  value  was  found  on  the  eighth 
and  ninth  days  of  fasting  with  one  of  the  animals.  Usually  the  heat- 
production  during  fasting  was  more  nearly  6,500  calories,  being  somewhat 
lower  on  the  second  day  than  on  the  first  day  of  fasting.  On  the  fifth  and 
sixth  days  in  the  case  of  cow  885  the  total  heat-production  was  6,557 
calories,  or  essentially  the  same  as  her  metabolism  earlier  in  the  fast. 

On  the  eighth  and  ninth  days  of  fasting  with  two  other  animals,  6,061 
and  6,302  calories  are  recorded.  Information  is  not  given  as  to  the  number 
of  hours  spent  by  the  animals  in  standing  and  lying.  Our  own  findings 
indicate,  however,  that,  when  fasting,  animals  are  wont  to  spend  more 
time  in  the  lying  than  in  the  standing  position.  Thus,  in  the  4-day  experi¬ 
ments  with  steers  E  and  F  (see  Table  53,  p.  195),  on  only  one  of  the  fasting 
days  did  the  animal  stand  more  than  12  hours,  that  is,  on  February  4-5, 
steer  E  stood  for  17  hours  and  lay  down  for  7  hours.  In  our  series  of  3-day 
experiments  (Table  52,  p.  186)  longer  periods  of  standing  were  more  fre¬ 
quently  observed.  For  purposes  of  discussion,  however,  if  one  assumes 
that  these  heat  values,  as  recorded  by  Braman,  represent  the  metabolism 
during  a  day  of  12  hours  standing  and  12  hours  lying,  they  could  be  brought 
to  the  basis  of  24  hours  lying  by  being  reduced  approximately  4.5  per  cent, 
granting  that  the  difference  between  the  metabolism  during  24  hours  lying 
and  24  hours  standing  is  9  per  cent,  as  derived  from  the  data  of  Fries  and 
Kriss.  On  the  other  hand,  if  one  assumes  that  the  animals  were  standing 
the  entire  time,  which  is  highly  improbable,  the  reduction  could  be  as 
high  as  9  per  cent.  On  this  last  assumption,  and  assuming  an  average 
fasting  katabolism  of  6,500  calories  for  cows  886  and  874,  the  corrected 
fasting  katabolism  would  be  approximately  6,000  calories.  Since  cows  886 
and  874  weighed  approximately  400  kg.,  their  surface  area  would  be  not 
far  from  4.7  square  meters,  according  to  the  curve  in  Fig.  8  (p.  155).  Their 
24-hour  heat-production  per  square  meter  of  body-surface  would  therefore 
be  approximately  1,280  calories,  on  the  basis  of  24  hours  lying.  The  com- 


°  Braman,  Journ.  Biol.  Chem.,  1924,  60,  Table  I,  p.  82. 


216 


METABOLISM  OF  THE  FASTING  STEER 


putation  for  the  smaller  cow  887,  which  weighed  about  320  kg.  and  had 
an  observed  total  metabolism  of  6,061  calories,  would  give  about  1,350 
calories  per  square  meter  of  body-surface  per  24  hours. 

This  analysis  leads  us  to  believe  that  the  true  basal  or  fasting  katabolism 
of  these  three  cows  is  much  more  nearly  1,300  calories  per  square  meter 
of  body-surface  than  967  calories,  the  average  value  derived  from  the 
fasting  katabolism  as  computed  from  two  feed-levels.  Indeed,  this  average 
value  of  1,300  calories  is  about  35  per  cent  higher  than  the  computed 
fasting  katabolism  of  these  animals.  Singularly  enough,  the  article  pub¬ 
lished  by  Cochrane,  Fries,  and  Braman  in  1925  gives  no  reference  whatso¬ 
ever  to  the  fasting  values  reported  by  Braman  in  1924,  although  we  are 
inclined  to  think  that  this  may  possibly  be  due  to  a  recognition  of  a  necessity 
for  some  further  revision.  Our  own  experience  with  the  effect  of  different 
feed-levels  on  fasting  metabolism  warrants  the  assertion  that  the  fasting 
katabolism  of  cattle  per  square  meter  of  body-surface  per  24  hours  is 
approximately  1,300  calories,  save  during  prolonged  fasting  or  fasting 
following  extreme  undernutrition.  If  the  basal  katabolism  of  cattle  in 
the  lying  position  is  found  to  be  as  high  as  1,300  calories,  the  comparison 
of  this  value  with  that  commonly  assumed  for  man  and  woman  can  be 
made  only  in  full  recognition  of  the  fact  that  the  cattle  show  a  value 
approximately  35  or  40  per  cent  above  that  for  humans,  and  this  is  entirely 
at  variance  with  the  hypothesis  of  E.  Yoit  and  his  followers. 

The  fact  that  the  computation  of  the  fasting  katabolism  from  experi¬ 
ments  with  two  different  quantities  of  the  same  feed  gives  results  far  lower 
than  those  noted  when  actual  measurements  are  made  of  the  fasting 
katabolism  is  due,  we  believe,  to  an  inherent  error  in  the  experimental 
procedure.  After  the  steer  has  been  on  submaintenance  rations  for  some 
time,  his  metabolism  would  not  represent  strictly  the  metabolic  effect  of 
the  submaintenance  ration,  since,  as  has  already  been  stated,  the  metabo- . 
lism  at  this  point  would  also  be  profoundly  lowered  by  the  undernourished 
condition.  The  computation  of  the  fasting  katabolism  from  the  metabolism 
at  maintenance  and  submaintenance  levels,  therefore,  gives  results  too  low 
when  the  submaintenance  metabolism  is  measured  after  the  animal  has 
begun  to  draw  materially  on  its  own  body-tissue  for  support  In  our  own 
experiments,  for  example,  the  submaintenance  ration  was  given  for  three 
or  more  weeks  prior  to  the  measurement  of  its  effect.  This  procedure  at 
the  time  was  thought  necessary  on  the  conventional  basis  that  the  animal 
should  be  adjusted  to  the  food-level  and  thus  have  a  metabolism  propor¬ 
tional  to  the  food  intake.  The  measurement  therefore  did  not  represent 
the  effect  of  the  reduced  feed  intake  with  the  consequently  lessened  diges¬ 
tive  activity  and  also  the  consequent  decrease  in  intestinal  fermentation, 
because  the  metabolism  at  this  stage  was  materially  altered  by  under- 
nutrition,  i.  e.,  by  drafts  upon  the  body  organism.0  When  feed  is  cut  from 

°  It  has  been  definitely  shown  (Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324, 
1923)  that  when  the  animal  is  forced  to  draw  on  his  own  body-tissue  for  support,  the  metabolism 
is  depressed  to  an  abnormally  low  level,  since  the  animal  parts  with  his  own  body-tissue,  even  for 
purposes  of  self-preservation,  only  with  the  limit  of  economy,  all  body  activities  being  curtailed 
to  save  tissue. 


THE  BASAL  METABOLISM  OF  STEERS 


217 


maintenance  to  submaintenance  there  must  be  some  point  during  the  transi¬ 
tional  stage  of  metabolism  representing  the  basal  condition  before  it  is 
affected  by  undernutrition.  From  the  previous  discussion  of  the  metabolic 
plateaus  it  would  seem  that  this  point  could  best  be  approximated  during 
the  second  24-hour  period  after  feed  reduction,  an  additional  day  being 
possibly  added  as  a  check.  In  other  words,  a  5-day  respiration  experiment, 
in  which  the  first  two  days  should  represent  maintenance,  the  third  would 
represent  a  mixed  effect,  and  the  fourth  and  fifth  days  would  represent 
the  beginning  of  the  submaintenance  plateau  (i.  e.,  the  level  of  metabolism 
as  determined  by  the  submaintenance  ration  before  the  effect  of  under- 
nutrition  has  markedly  manifested  itself) ,  appears  to  form  the  most  logical 
method  of  procedure. 

Whether  the  same  difficulty  would  be  found  if  the  initial  feed-level  were 
above  maintenance  and  the  lower  feed-level  were  at  maintenance  is  still 
open  for  investigation,  as  our  experiments  were  not  made  with  this  point 
in  view.  Since  most  studies  in  this  field  have  been  made  upon  the  basis  of 
maintenance  versus  submaintenance,  it  would  seem  that  this  explanation 
of  the  difference  between  the  computed  fasting  katabolism  and  that  actually 
existing  with  the  animals  may  serve  a  helpful  purpose. 

From  the  data  in  the  series  of  4-day  experiments  with  steers  E  and  F, 
a  study  of  a  number  of  important  problems  outside  of  the  field  of  fasting 
metabolism  becomes  incidentally  available,  such  as  the  relative  effect  of 
reduction  in  food  consisting  of  timothy  or  alfalfa  hay.  Thus,  in  the  case 
of  steer  E,  there  apparently  was  a  reduction  in  the  total  heat-production 
of  about  3,500  calories  as  a  result  of  reducing  the  ration  from  7.00  kg.  to 
3.5  kg.  of  timothy  hay.  On  the  other  hand,  a  reduction  in  the  same  amount 
of  alfalfa  hay  resulted  in  a  total  daily  reduction  of  3,800  calories.  With 
steer  F,  similar  reductions  resulted  in  a  decrease  of  about  2,900  calories 
from  timothy  hay  and  3,400  calories  from  alfalfa  hay. 

To  make  such  a  series  of  experiments  complete,  obviously  a  careful 
analysis  of  the  digestibility  of  the  hay  and  a  determination  of  the  nitrogen 
balance  should  be  made.  On  the  other  hand,  the  extra  precautions  taken 
to  secure  uniformity  of  content  of  digestive  tract  during  submaintenance 
feeding  (in  those  experiments  where  the  effect  of  curtailment  of  ration  was 
compared  with  the  effect  of  a  full  ration)  by  the  conventional  method  of 
preparing  the  animal  with  a  preliminary  feeding-period  of  two  or  more 
weeks,  undoubtedly  resulted  in  a  change  in  the  nutritive  level  of  the  animal. 
This  has  been  established  by  the  comparative  results  of  the  various  fasts. 
It  would  seem,  therefore,  as  if  the  question  of  digestibility  on  lower  rations 
should  be  studied  independently  and  not  combined  with  a  study  of  the 
gaseous  exchange.  It  is  our  purpose  to  discuss  such  data  from  these  experi¬ 
ments  as  lend  themselves  to  a  study  of  these  different  angles  later,  as  more 
information  is  secured  not  only  upon  steers  but  upon  dry  cows,  with  which 
we  are  at  present  carrying  out  observations.  The  data  presented  here  are 
therefore  primarily  such  as  bear  directly  on  the  effect  of  the  character  and 
quantity  of  the  previous  feed-level  and  the  effect  of  environmental  tempera¬ 
ture  upon  the  fasting  katabolism. 


218 


METABOLISM  OF  THE  FASTING  STEER 


This  discussion  is  of  chief  significance  solely  from  the  standpoint  of 
comparative  physiology.  From  the  practical  standpoint  it  may  be  assumed 
that  in  general  a  sufficiently  close  approximation  of  the  fasting  katabolism 
can  be  determined  on  animals,  while  standing,  about  32  hours  after  the  last 
food,  and  that  if  a  satisfactory  reduction  in  the  measurement  thus  obtained 
is  made  for  lying,  the  basal  metabolism  during  24  hours  lying  may  be 
computed.  This  procedure  should  give  a  value  which  is  suitable  as  a  base¬ 
line  in  studies  of  the  superimposed  effects  of  various  factors,  provided  the 
experiments  are  made  shortly  after  this  basal  determination.  The  value 
will  not  be  uniform  with  different  animals,  even  if  the  metabolism  is  com¬ 
puted  on  the  basis  of  surface  area.  It  will  not  be  uniform  for  the  same 
animal  at  different  times,  particularly  when  there  are  profound,  changes 
in  the  nutritive  state,  for  even  with  essentially  the  same  nutritive  state 
considerable  differences  do  occur,  as  is  seen  in  Table  48  (p.  173). 

In  consideration  of  the  great  difference  between  the  fasting  katabolism 
computed  on  the  basis  of  the  metabolism  at  two  different  feed-levels  and 
that  actually  found  by  calorimetric  and  gaseous  metabolism  measurements 
during  prolonged  fasting,  it  would  seem  as  if  the  computation  method,  at 
least  in  its  present  form,  has  limited  value. 

The  Minimum  Heat-production  of  Steers  per  Square  Meter  of  Body-surface  per  24 

Hours 

In  the  discussion  of  the  plateau  level  in  the  metabolism  of  these  fasting 
steers  it  was  pointed  out  (see  pp.  213  to  216)  that  the  lowest  level  during 
fasting  was  about  1,300  calories  per  square  meter  of  body-surface  per  24 
hours,  i.  e.,  higher  than  the  conventional  1,000  calories  ascribed  to  all  warm¬ 
blooded  animals  as  a  class.  An  examination  of  all  our  values  indicating 
the  minimum  heat-production  per  square  meter  of  body-surface  which  may 
be  expected  with  steers  under  numerous  different  conditions,  irrespective 
of  whether  a  plateau  has  been  reached  in  the  metabolism,  becomes  of 
interest  for  purposes  of  comparison  with  other  researches  made  on  this 
basis. 

The  lowest  values  for  the  24-hour  heat-production  per  square  meter  of 
body-surface  occur  in  the  series  of  experiments  involving  three  or  four 
half-hour  periods  of  measurement.  With  steer  C  the  lowest  value  is  1,060 
calories  on  January  30,  1923,  49  hours  after  food.  With  steer  D  the  lowest 
value  is  1,190  calories,  also  the  same  number  of  hours  after  food  and  at 
about  the  same  date,  i.  e.,  January  27, 1923.  (See  Tables  44  and  45,  pp.  166 
and  168.)  In  both  of  these  instances  the  steers  were  at  a  maintenance 
level  of  nutrition.  With  steer  C  another  low  value  of  1,100  calories  was 
found  on  the  second  day  of  the  fast  in  March  1924,  following  submainte¬ 
nance  feeding.  With  steer  F,  a  younger  animal,  the  lowest  recorded  value 
is  1,540  calories,  24  hours  after  the  last  food  on  February  19,  1924,  which 
happened  to  be  the  first  day  after  a  fasting  experiment.  With  steer  E  it 
was  1,520  calories  on  December  28,  1923,  when  the  animal  was  upon  a 
submaintenance  level.  (See  Table  57,  p.  232.) 

In  the  continuous  3-day  experiments  in  1924,  the  heat  values  are  based 
not  upon  three  or  four  half-hour  periods,  but  upon  individual  8-hour 


THE  BASAL  METABOLISM  OF  STEERS 


219 


periods.  In  this  series  the  minimum  heat-production  of  steer  C  was  1,580 
calories  on  April  25,  that  of  steer  D  was  1,820  calories  on  May  15,  that 
of  steer  E  was  1,890  calories  on  April  11,  and  that  of  steer  F  was  1,850 
calories  on  April  1.  (See  Table  52,  p.  186.)  These  measurements  were 
all  made  while  the  animals  were  fasting,  but  immediately  following  mainte¬ 
nance  rations.  In  the  4-day  experiments  in  1925,  when  the  metabolism 
was  also  measured  in  8-hour  periods,  lower  values  were  found  with  the 
younger  animals.  Thus,  steer  E  had  a  minimum  24-hour  heat-production 
of  1,230  calories  per  square  meter  of  body-surface  in  the  8-hour  period 
beginning  32  hours  after  food  on  May  6-7,  1925,  and  steer  F  of  1,330 
calories  in  the  8-hour  period  beginning  56  hours  after  food  on  May  14-15, 
1925.  In  both  instances  the  steers  were  fasting  after  a  submaintenance 
level  of  nutrition. 

The  lowest  values  found  with  steers  C  and  D  were,  therefore,  1,060  and 
1,190  calories,  and  with  steers  E  and  F  1,230  and  1,330  calories,  respectively. 

A  careful  examination  of  the  conditions  under  which  these  very  low 
values  for  steers  C  and  D  were  obtained  brings  out  the  fact  that  the 
metabolism  of  both  animals  had  been  measured  at  a  very  low  temperature 
on  one  day  and  at  a  much  higher  temperature  on  the  following  day.  Thus, 
with  steer  C  on  January  29,  1923,  at  a  chamber  temperature  of  2.9°  C., 
the  heat-production  was  1,740  calories  per  square  meter  of  body-surface. 
On  the  next  day  the  temperature  of  the  chamber  was  raised  to  24.9°  C. 
and  the  metabolism  per  square  meter  of  body-surface  fell  to  1,060  calories. 
With  steer  D  the  situation  was  similar,  in  that  on  January  26  the  chamber 
temperature  was  8.8°  C.  and  the  heat-production  1,850  calories,  and  on 
the  next  day  the  temperature  was  raised  to  28.3°  C.  and  the  metabolism 
fell  to  1,190  calories.  In  each  case  the  second  experiment  at  the  high 
temperature  was  made  24  hours  later  than  the  first  experiment,  that  is, 
49  hours  after  food.  As  such  large  decreases  in  metabolism  were  not 
obtained  with  these  steers  during  the  first  three  days  of  fasting  after  full 
feeding  in  the  series  of  long  fasts,  it  is  evident  that  these  abnormally  low 
values  are  the  result  of  the  pronounced  effect  of  the  sudden  transition  from 
a  cold  to  a  warm  environment.0  This  conclusion  is  supported  by  another 
experiment  with  steer  D  on  January  18  and  19,  1923.  On  the  first  day 
the  chamber  temperature  was  3.4°  C.  and  the  metabolism  was  1,730 
calories  per  square  meter  of  body-surface.  On  the  next  day  the  temperature 
in  the  chamber  was  raised  to  28.2°  C.  and  the  metabolism  fell  to  1,290 
calories.  An  examination  of  all  our  data  shows  that  in  practically  every 
instance  a  striking  rise  in  temperature  resulted  in  a  greatly  lowered 
metabolism.  When  the  temperature  was  12°  C.  or  above,  however,  the 
change  in  metabolism  was  no  greater  than  would  be  expected  on  one  or 
two  successive  fasting  days. 

This  profound  decrease  in  the  metabolism  of  steers  C  and  D,  although 
apparently  due  to  a  sudden  change  of  temperature,  is  difficult  of  further 

a  A  similar  explanation  does  undoubtedly  account  for  the  low  standard  metabolism  of  1,180 
calories  per  square  meter  of  body-surface  per  24  hours  noted  with  steer  C  on  December  20,  1923, 
when  on  a  maintenance  ration.  In  this  instance  the  steer  had  been  for  approximately  24  hours 
at  a  stall  temperature  of  3°  C.  and  was  then  studied  in  the  respiration  chamber  at  a  temperature 
of  19.5°  C.  (See  Table  55,  p.  226.) 


220 


METABOLISM  OF  THE  FASTING  STEER 


explanation  without  other  data  on  this  point.  The  metabolism  during  the 
first  day  of  fasting  on  the  cold  days,  which  was  not  far  from  1,700  calories 
per  square  meter  of  body-surface,  is  not  so  high  with  these  animals  as, 
for  example,  on  the  first  day  of  the  long  fasting  experiments  (see  Table 
50) ,  and  it  is  not  indicative  of  an  especially  high  metabolism  produced  by 
severe  cold.  The  transition  from  the  cold  to  the  warm  environment  evi¬ 
dently  had  an  immediate  pronounced  effect  in  lowering  the  metabolism, 
perhaps  to  be  explained  by  the  fact  that  prior  to  each  metabolism  measure¬ 
ment  the  animals  had  been  in  their  metabolism  stalls  for  only  about  16 
hours  at  a  temperature  essentially  the  same  as  that  which  prevailed  in  the 
respiration  chamber  during  the  experiment. 

There  are  only  a  few  instances  where  the  conditions  were  reversed  and 
the  metabolism  was  measured  at  a  high  environmental  temperature  on  the 
first  day  of  fasting  and  at  a  low  temperature  on  the  second  day.  The  most 
striking  illustration  is  the  experiment  with  steer  D  on  February  2  and  3, 
1923.  On  February  2  the  chamber  temperature  was  27.9°  C.  and  the  heat- 
production  was  1,610  calories  per  square  meter  of  body-surface.  The 
records  of  stall  temperature  show  that  from  8  p.  m.  on  February  2  until 
the  time  of  the  respiration  experiment  on  February  3  the  environmental 
temperature  was  essentially  12°  C.  On  February  3  the  chamber  tempera¬ 
ture  was  7.3°  C.  and  the  heat-production  was  1,450  calories.  In  this 
instance  the  drop  in  metabolism  was  hardly  more  than  would  be  expected 
with  continued  fasting,  and  the  change  in  temperature  apparently  had  no 
influence  upon  the  metabolism.  Because  of  these  sudden  changes  in  metab¬ 
olism  following  a  change  in  temperature,  our  plan  of  experimentation 
in  studying  the  influence  of  environmental  temperature  was  altered  in  the 
1925  series  in  that  the  animals  were  kept  for  two  weeks  or  more  prior  to 
an  experiment  at  the  specific  temperature  at  which  they  were  to  be  studied 
in  the  respiration  chamber. 

With  humans  there  is  almost  no  evidence  to  explain  this  pronounced 
lowering  in  metabolism  with  the  change  from  a  very  cold  to  a  warm  envi¬ 
ronment.  The  Nutrition  Laboratory  has  for  many  years  been  searching, 
without  success,  for  some  factor  or  combination  of  conditions  that  would 
result  in  a  lowering  of  the  so-called  “basal  metabolism”  of  humans.  Pro¬ 
found  undernutrition  and  fasting  do  lower  it,  but  these  are  not  immediate, 
superimposed  factors.  It  has  been  maintained  that  a  warm  bath  lowers 
the  metabolism,  and  that  the  basal  metabolism  can  only  be  secured  when 
the  body  is  immersed  in  water  at  about  35°  C.°  This  problem  was  studied 
at  the  Nutrition  Laboratory  with  several  subjects,  and  it  was  noted  that 
the  metabolism  was  not  lowered  by  immersion  in  the  bath.* 6  More  recently 
Delcourt-Bernard  and  Andre  Mayer  have  reported0  that  they  have  occa¬ 
sionally  noted  a  very  low  metabolism  with  humans  after  prolonged  immer¬ 
sion  in  a  warm  bath,  indicating  an  after-effect  of  the  bath.  It  is  possible 
that  with  these  steers  in  the  somewhat  rapid  transition  from  the  cold  to 

“  Lefevre,  Bull.  Soc.  Sci.  d’Hygiene  Alimen.,  1922,  10,  p.  595. 

6  Benedict  and  Benedict,  Bull.  Soc.  Sci.  d’Hygifene  Alimen.,  1924,  12,  p.  541;  ibid.,  Proc. 
Nat.  Acad.  Sci.,  1924,  10,  p.  495. 

c  Delcourt-Bernard  and  Mayer,  Compt.  Rend.,  1925,  92,  p.  62. 


THE  BASAL  METABOLISM  OF  STEERS 


221 


the  warm  environment  there  may  be  a  period  of  relaxation  or  adjustment 
to  the  temperature,  which  may  actually  result  temporarily  in  a  lower 
heat-production.  It  is  unfortunate  that  the  tests  of  this  after-effect  of 
the  warm  environmental  temperature  were  not  prolonged  sufficiently  to 
note  whether  this  low  metabolism  remained  constant  or  whether  there  was 
a  later  reaction.  This  problem  should  be  studied  in  the  near  future. 

Of  great  importance  to  general  physiology,  however,  is  the  fact  that,  at 
least  with  steers  C  and  D,  there  are  two  instances  of  a  heat-production 
per  square  meter  of  body-surface  actually  approaching  1,000  calories,  the 
value  commonly  assumed  to  represent  the  heat-production  of  all  warm¬ 
blooded  animals.  The  fact  that  these  values  were  found  only  under  the 
special  condition  of  an  extreme  change  in  temperature  implies  that  we 
have  to  deal  here  not  with  a  persistent  level  of  basal  metabolism  but  with 
a  special,  imposed  condition,  the  effect  of  which,  in  all  probability,  is 
transitory.  When  steer  C  was  subjected  to  submaintenance  rations  and 
then  to  prolonged  fasting,  the  heat-production  per  square  meter  of  body- 
surface  was,  to  be  sure,  as  low  as  1,110  calories.  But  since  this  value 
reflects  the  influence  of  the  superimposed  effect  of  undernutrition,  it  can 
hardly  be  compared  directly  with  values  found  with  animals  at  a  mainte¬ 
nance  level  of  nutrition,  even  after  they  have  undergone  several  days  of 
fasting.  Fasting  per  se,  provided  the  initial  level  of  nutrition  has  not  been 
too  greatly  lowered  by  a  submaintenance  ration,  results  in  a  heat-produc¬ 
tion  per  square  meter  of  body-surface  per  24  hours  much  nearer  1,700 
calories  during  the  first  48  hours  than  the  1,060  and  1,190  calories  noted 
with  these  two  animals  following  the  extreme  change  in  temperature. 

THE  PHYSIOLOGICAL  SIGNIFICANCE  OF  SURFACE  AREA  AND  ITS  RELATIONSHIP  TO 

HEAT-PRODUCTION 

For  the  comparison  of  the  true  basal  metabolism  of  these  steers  with 
that  of  man,  determined  under  the  well-known  prescribed  conditions  of 
the  post- absorptive  state  and  complete  muscular  repose,  measurements 
made  during  periods  of  quiet  lying,  at  least  48  hours  after  the  last  food, 
are  presumably  the  best.  Since  all  of  our  heat  values  were  determined 
when  the  steers  were  standing  or  both  lying  and  standing,  they  probably 
should  be  corrected  for  the  extra  effort  of  standing  (see  p.  211),  if  they  are 
to  represent  conditions  similar  to  those  under  which  the  basal  metabolism 
of  humans  is  measured.  We  have  already  seen  (p.  214)  that  the  average 
heat-production  per  square  meter  of  body-surface  of  these  steers  42  to  56 
hours  after  food,  which  would  correspond  essentially  to  the  12-hour  interval 
required  with  man,  would  be  about  1,700  calories  at  the  maintenance  level 
and  from  1,600  to  1,700  calories  at  the  submaintenance  level.  If  these 
values  were  corrected  for  the  extra  effort  of  standing,  they  would  still 
be  materially  above  1,300  calories  on  the  average. 

This  value  of  1,300  calories  per  square  meter  of  body-surface  may  there¬ 
fore  be  taken  as  the  probable  basal  metabolism  or  the  lowest  metabolism 
of  these  ruminants,  which  will  remain  reasonably  constant  for  four  or  five 
days  of  fasting,  after  which  the  metabolism  will  fall  off,  as  indicated  in 
Table  50.  The  popular  impression  that  the  metabolism  is  1,000  calories 


222 


METABOLISM  OF  THE  FASTING  STEER 


per  square  meter  of  body-surface  for  all  warm-blooded  animals  must,  we 
believe,  be  looked  upon  with  great  reserve  in  a  refinement  such  as  this. 
The  basal  metabolism  of  man  has  been  found  with  considerable  exactness 
to  be,  on  the  average,  not  far  from  900  calories  per  square  meter  of  body- 
surface.  With  these  steers,  however,  the  basal  values  are  not  far  from 
1,300  calories,  or  approximately  45  per  cent  higher. 

The  rectal  temperatures  of  these  steers  were  about  1  degree  higher  than 
the  rectal  temperature  of  the  average  man  (37°  C.).  Physiologists,  how¬ 
ever,  in  considering  this  law  of  surface  area  and  the  heat-production  per 
square  meter  of  body-surface,  are  inclined  to  disregard  differences  in  body 
temperature  between  species,  although  admitting  that  in  the  individual 
human  small  rises  in  temperature  actually  result  in  greater  heat-production. 
Emphasis  has  been  laid  upon  the  matter  of  equal  conditions  of  nutrition  in 
comparing  various  animals.  We  have  seen  in  our  study  of  steers  that  the 
heat-production  is  lower  at  the  submaintenance  level  than  at  the  mainte¬ 
nance  level,  and  that  during  fasting  it  is  somewhat  lower  than  at  the 
submaintenance  level.  One  of  the  most  extensive  uses  to  which  the  meas¬ 
ured  heat-production  of  man  and  the  standard  values  are  put,  however,  is 
the  clinical  application  to  pathological  cases,  in  which  undemutrition  plays 
a  large  role.  We  have  yet  to  see  indications  where  differences  in  the  nutri¬ 
tive  states  of  humans  have  been  seriously  taken  into  consideration  in 
assessing  the  measured  heat  metabolism  and  comparing  it  with  normal 
standards. 

The  problem  of  establishing  a  basal  heat-production  with  ruminants, 
which  may  be  used  for  the  comparison  of  the  influence  of  the  ingestion 
of  various  types  of  food  and  the  influence  of  various  levels  of  feeding,  is 
by  no  means  solved.  Uniformity  may  not  be  hoped  for  with  different 
animals.  Differences  with  different  feed-levels  will  undoubtedly  be  found. 
Differences  with  different  environmental  temperatures  have  already  been 
noted,  especially  on  the  lower  feed-levels.  It  is  believed  that  a  study  of 
the  reaction  of  an  animal  in  a  given  nutritive  state  to  the  drafts  upon 
body  material,  as  exemplified  by  these  short  2-day  fasting  experiments, 
and  a  study  of  the  effect  of  various  rations  in  enabling  the  animal  to 
withstand  such  drafts  upon  body  material  when  equal  states  of  nutrition 
are  assumed,  may  be  of  great  value  in  estimating  not  only  the  nutritive 
states  of  an  animal,  but  the  actual  value  of  various  feeds  to  the  animal  for 
growth,  maintenance,  and  protection  against  drafts  upon  body  material. 

Influence  of  the  Ingestion  of  Food 
The  Immediate  Reaction  to  the  Ingestion  of  Food  After  a  Prolonged  Fast 

In  view  of  the  difficulties  experienced  with  humans  during  realimentation 
after  a  long  fast  or  after  a  long  period  of  undemutrition,®  it  was  considered 
important  to  note  the  metabolic  reaction  of  these  steers  to  the  ingestion 
of  food  after  prolonged  fasting.  A  number  of  respiration  experiments  were 
therefore  made  at  the  end  of  some  of  the  long  fasts,  and  the  effect  of  the 
first  feed  following  the  fast  was  studied  in  continuous  half-hour  periods 

°  Benedict,  Carnegie  Inst.  Wash.  Pub.  No.  203,  1915,  p.  49;  Benedict,  Miles,  Roth-  and  Smith 
Carnegie  Inst.  Wash.  Pub.  No.  280,  1919,  p.  683. 


INFLUENCE  OF  THE  INGESTION  OF  FOOD 


223 


for  from  five  to  eight  hours  following  the  ingestion  of  feed,  while  the  animal 
remained  inside  the  respiration  chamber.  Information  was  thus  obtained 
on  the  change  in  the  respiratory  quotient  resulting  from  ingestion  of  food, 
and  particularly  on  the  change  produced  in  the  actual  metabolism,  as 
indicated  by  the  carbon-dioxide  excretion.  From  1  to  2  kg.  of  chopped 
hay  were  usually  offered  to  the  steers,  and  in  some  cases  a  small  amount 
of  meal,  not  far  from  1  kg. 

In  general,  the  animals  were  extremely  slow  about  eating-  When  hay 
alone  was  offered  they  would  take  an  hour  or  more  to  consume  even  a 
moderate  amount,  such  as  1,000  to  2,000  grams.  The  grain,  being  more 
palatable,  was  apparently  relished  more  and  eaten  with  greater  vigor.  It 
would  seem  as  if  there  was  an  instinctive  control  which  retarded  the  steer 
from  overeating.  It  was  believed  at  first  that  a  study  of  the  immediate 
effect  of  feeding  could  be  superimposed  at  the  end  of  a  fasting  experiment, 
but  the  small  amounts  of  hay  consumed  made  such  experiments  unsatis¬ 
factory  and  almost  without  significance. 

A  comparison  of  the  carbon-dioxide  production  on  the  last  day  of  the 
fast  with  the  carbon-dioxide  production  measured  in  the  different  half-hour 
periods  of  the  respiration  experiment  made  almost  immediately  after  the 
animal  had  been  fed,  shows  that  during  the  first  half-hour  period  there 
was  invariably  a  striking  increase  in  the  metabolism.  In  the  subsequent 
periods  the  carbon-dioxide  production  was  irregular,  with  no  clear  indica¬ 
tion  of  a  continual  increase  during  the  5  to  8  hours  under  investigation. 
There  was  always  a  pronounced  rise  in  the  respiratory  quotient,  which 
slowly  though  continually  increased.  The  general  conclusion  is  that  there 
is  an  immediate  response  to  the  ingestion  of  food,  probably  depending 
somewhat  upon  the  length  of  time  that  the  animals  were  occupied  in  eating 
the  relatively  small  amounts  consumed.  After  the  initial  response,  these 
small  amounts  of  feed  did  not  further  stimulate  the  metabolism. 

The  Metabolic  Stimulus  of  Feeding-stuffs 

The  metabolism  of  the  organism  is  stimulated  or  raised  above  the  basal 
requirements  by  the  processes  of  digestion  and  utilization  of  food  much  as 
the  fire  in  a  furnace  would  flare  up  when  fanned  by  a  blower.  The  separate 
evaluation  of  the  economic  cost  of  such  overhead  processes  with  each  feed¬ 
ing-stuff  is  the  critical  feature  in  the  determination  of  the  so-called  “net 
energy  values”  of  feeding-stuffs.  The  attempt  to  determine  this  economic 
cost  by  measuring  the  metabolism  at  two  different  feed-levels  has,  we 
believe,  resulted  in  the  utilization  of  an  unduly  low  figure  for  the  metabolism 
following  the  lower  food-level.  This  experimental  plan  calls  for  prolonged 
feeding  on  the  curtailed  ration  prior  to  the  measurement  of  the  metabolism, 
in  order  to  secure  uniformity  of  contents  in  the  intestinal  tract  and  hence 
uniformity  in  the  determination  of  the  digestion  coefficients.  By  this 
procedure  the  animal  is  brought  to  a  lower  metabolic  plane  by  the  dual 
effect  of  the  actual  reduction  in  feed  and  the  condition  of  undernutrition 
at  least  begun  during  the  3  weeks’  period  of  submaintenance  feeding.  On 
the  other  hand,  if  the  metabolism  of  an  animal  is  first  determined  while 
he  is  on  maintenance  feed  and  then  shortly  thereafter  at  essentially  the 
fasting  stage,  the  difference  between  these  two  levels  should  indicate  the 


224 


METABOLISM  OF  THE  FASTING  STEER 


increased  metabolism  of  the  organism  due  to  the  ingestion  of  food.  This 
method  is  certainly  justifiable  when  animals  are  fed  a  maintenance  ration. 
In  order  to  compare  the  metabolism  on  maintenance  and  submaintenance 
rations,  or  on  a  ration  50  per  cent  below  maintenance,  as  was  the  case  in 
our  research,  in  all  probability  the  curtailment  should  not  take  place  more 
than  at  the  most  one  or  two  days  before  the  actual  experiment,  as  otherwise 
one  will  be  running  into  the  dangers  of  incipient  undernutrition  with  its 
well-known  depressing  effect  upon  metabolism. 

Experiments  on  this  special  point  have  not  yet  been  made,  although  they 
are  in  our  experimental  plan.  If  we  examine  the  data  for  the  4-day 
experiments  with  steers  E  and  F  (see  Table  53,  p.  195)  and  confine  our¬ 
selves  to  those  experiments  in  which  maintenance  feeding  with  7  kg.  of 
either  timothy  or  alfalfa  hay  is  involved,  and  eliminate  any  experiments 
with  unduly  low  chamber  temperatures,  we  may  obtain  some  evidence 
regarding  the  increase  in  metabolism  due  to  the  feed.  It  will  be  recalled 
that  in  these  experiments  the  animal  was  fed  7  kg.  of  hay  for  at  least  two 
weeks  prior  to  the  experiment. 

The  24-hour  heat-production  of  steer  E  during  maintenance  feeding  on 
timothy  hay  was  reasonably  constant  at  11.6  therms0  on  December  12  to 
14.  In  the  experiment  beginning  32  hours  after  the  withholding  of  this 
ration,  i.  e.,  during  the  stage  of  so-called  “fasting  katabolism,”  the  heat- 
production  was  7.7  therms  or  3.9  therms  lower.  Reversing  the  argument, 
one  can  state  that  a  fasting  katabolism  of  7.7  therms  was  raised  3.9  therms 
by  the  regular  ingestion  of  7  kg.  of  timothy  hay.  In  other  words,  there 
was  an  increase  in  metabolism  of  51  per  cent.  Similarly,  in  the  experiment 
from  February  27  to  March  3* * 6  the  initial  metabolism  with  7  kg.  of  timothy 
hay  was  11.1  therms.  In  the  basal  experiment  beginning  32  hours  after 
the  last  food  it  was  7.8  therms,  or  3.3  therms  lower.  There  was,  therefore, 
in  this  case  an  increase  of  42  per  cent  with  the  ingestion  of  7  kg.  of  timothy 
hay.  With  alfalfa  hay  the  heat-production  in  the  March  experiment  was 
11.5  therms  during  the  two  days  on  feed  and  7.0  therms  in  the  period 
beginning  32  hours  after  the  last  food.  The  increase  due  to  the  hay  was 
therefore  4.5  therms  or  64  per  cent.  The  experiment  of  April  14  to  17 
shows  a  heat-production  during  full  feeding  with  alfalfa  hay  of  11.5  therms 
and  32  hours  after  the  last  food  6.7  therms,  i.  e.,  an  increase  of  4.8  therms 
or  72  per  cent. 

With  steer  F  in  the  December  experiment  with  timothy  hay,  the  heat- 
production  was  11.9  therms  on  full  feed  and  32  hours  after  food  it  was 
8.1  therms.  The  increase  due  to  the  hay  was  thus  3.8  therms  or  47  per  cent. 
On  March  23  to  25  the  two  days  of  feeding  with  alfalfa  hay  resulted  in  a 
metabolism  of  12.5  therms,  which  fell  to  7.7  therms  on  the  second  day 
without  food.  The  difference  was  4.8  therms  or  62  per  cent.  In  a  second 
experiment  with  alfalfa  hay  in  April,  the  heat-production  on  full  feed  was 
12.3  therms  and  32  hours  after  food  was  7.5  therms.  The  increase  was  4.8 
therms  or  64  per  cent. 

°  We  use  the  Armsby  term  here,  since  in  practical  feeding  problems  it  apparently  has  distinct 

advantage  over  the  large  numeral  calories.  One  therm  is  equivalent  to  1,000  large  calories. 

6  The  low  environmental  temperature  obtaining  in  this  experiment  is  seemingly  without  effect. 


INFLUENCE  OF  THE  INGESTION  OF  FOOD 


225 


Thus  with  both  animals  it  is  clear  that  the  increase  in  metabolism  pro¬ 
duced  by  the  7  kg.  of  timothy  hay  was  not  far  from  50  per  cent,  but  that 
the  increase  produced  by  7  kg.  of  alfalfa  hay  was  nearer  60  per  cent.  On 
this  basis,  therefore,  the  so-called  “specific  dynamic  action,”  or  preferably 
the  “metabolic  stimulus,”  of  alfalfa  hay  is  measurably  higher  than  that 
of  timothy  hay.  On  the  other  hand,  as  has  been  pointed  out  before  this, 
the  basal  heat-production  with  alfalfa  hay,  determined  32  to  56  hours  after 
food,  is  perceptibly  lower  in  general  than  with  timothy  hay.  This  may 
possibly  be  accounted  for  by  the  fact  that  the  alfalfa  experiments  were 
at  the  end  of  the  series  with  both  animals.  In  other  words,  the  steers  had 
been  undergoing  a  fairly  rapid  series  of  2-day  fasts  and  undoubtedly  their 
nutritive  condition  must  have  been  at  a  somewhat  lower  level  at  the  end 
of  the  series  than  it  was  at  the  beginning,  in  spite  of  the  mild  attempts 
to  make  up  for  the  loss  between  experiments.  To  make  the  study  perfectly 
clear,  the  experimental  series  should  likewise  have  been  carried  out  in  the 
reverse  order.  But,  as  stated  frequently,  our  main  object  was  not  to  study 
the  relative  merits  of  alfalfa  and  timothy  hay. 

These  feeds  are  both  characterized,  as  is  most  roughage  for  animals,  by 
a  low  digestibility,  that  is,  they  are  approximately  50  per  cent  digestible. 
The  alfalfa  hay  is  richer  in  protein  than  is  the  timothy  hay,  which  is 
relatively  protein-poor.  Judging  from  experiments  on  mep  and  dogs,  the 
normal  increase  in  metabolism  due  to  the  ingestion  of  food  is  by  no  means 
of  the  same  order  of  magnitude  as  observed  with  these  ruminants.  Thus, 
Benedict  and  Carpenter®  found  in  three  8-hour  experiments,  when  the  sub¬ 
ject  ate  enormous  amounts  of  food  at  one  meal  (the  fuel  value  of  which 
averaged  4,000  calories),  that  the  total  increment  in  heat  noted  in  the 
subsequent  8  hours  was  186,  229,  and  148  calories,  respectively.  On  the 
average  the  increase  was  23  calories  per  hour.  Since  the  heat-production 
was  about  70  calories  per  hour  when  these  subjects  were  resting,  it  can  be 
seen  that  during  these  eight  hours,  when  the  digestive  activity  was  greatest 
there  was  an  increase  of  only  about  30  per  cent  in  the  heat-production  due 
to  these  enormously  heavy  meals.  When  referred  to  the  actual  fuel  value 
of  the  meal  itself,  this  increase  (termed  by  the  authors  the  “cost  of  diges¬ 
tion”)  is  found  to  be  not  far  from  5  per  cent.  The  picture  is  entirely 
different  with  steers,  for  the  ingestion  of  7  kg.  of  hay,  of  which  one-half 
*  only  is  digestible,  produced  not  during  the  height  of  digestion  but  through¬ 
out  an  entire  24-hour  period  an  increase  in  the  total  heat-production  of 
50  per  cent  in  the  case  of  timothy  hay  and  60  per  cent  in  the  case  of  alfalfa 
hay.  In  the  case  of  the  men  the  protein  in  the  meal  accounted  in  appre¬ 
ciable  part  for  the  increase,  as  the  so-called  “specific  dynamic  action”  of 
protein  is  most  marked.  Timothy  hay,  however,  contains  little  protein, 
and  the  stimulating  effects  of  foods  are  on  an  entirely  different  plane  with 
ruminants  than  with  a  human  being.  These  large  increases,  we  believe, 
may  be  easily  accounted  for  by  the  nature  of  the  cleavages  which  carbo¬ 
hydrate  material  undergoes  in  its  passage  through  the  intestinal  tract. 
Indeed,  the  early  suggestion  of  Grouven,  that  carbohydrates  for  the  large 

0  Benedict  and  Carpenter,  Carnegie  Inst.  Wash.  Pub.  No.  261,  1918,  Table  249,  p.  337. 


226  METABOLISM  OF  THE  FASTING  STEER 


Table  55— Standard  metabolism  of  steer  C  at  different  levels  of  nutrition 


Car- 

Heat  produced  per 

In- 

Aver- 

bon 

24  hours 

Heart- 

di- 

Res- 

Stall 

tem¬ 

pera¬ 

ture 

Feed-level, 
and  dates 

Live 

weight 

rate 

per 

min- 

ble 

loss 

per 

cham¬ 

ber 

tern- 

oxide 

pro¬ 

duced 

pira- 

tory 

quo- 

Total 

Per 

Per 

Ac¬ 

tivity 

ute 

24 

pera- 

per 

tient 

500  kg. 

sq.  m. 

hours 

ture 

half 

hour 

Realimentation;  4  to  8 

cal. 

cal. 

cal. 

kg.  hay,  2  kg.  meal;1 

kg. 

kg. 

°C. 

°C. 

gm. 

ii 

Dec.  17,  1921 .... 

558.4 

40 

4.8 

21 

21.3 

56.7 

(0.82) 

8,100 

7,300 

1,440 

Dec.  22,1921.... 

570.0 

38 

2.2 

7 

11.3 

59.9 

(.82) 

8,600 

7,500 

1,510 

ii 

Jan.  23,  1922. . .  . 

567.6 

40 

6.4 

12 

20.3 

79.3 

(-82) 

11,400 

10,000 

2,000 

II 

Jan.  30,  1922. . . . 
Maintenance;  9  kg. 

572.2 

40 

24 

21.6 

81.0 

(.82) 

11,600 

10,100 

2,030 

hi 

hay:2 

Mar.  21,  1922... . 
Mar.  31,  1922.... 

596.0 

592.2 

8  60 

24.9 

71.6 

(.82) 

10,300 

8,600 

1,750 

ii 

40 

7.4 

20 

22.7 

66.4 

(.82) 

9,500 

8,000 

1,630 

ii 

Realimentation;  8  kg. 

hay: 

May  9,1922.... 

562.2 

34 

5.2 

18 

19.4 

66.1 

(.82) 

9,500 

8,400 

1,680 

ii 

Maintenance;  9  kg. 

hay,  2  kg.  meal:2 

5,600 

1,200 

ii 

Dec.  13,1922.... 

674.8 

40 

9.0 

18 

22.1 

51.5 

.79 

7,600 

Dec.  18,  1922 _ 

670.8 

40 

12.8 

26 

27.0 

69.4 

.78 

10,400 

7,800 

1,650 

ii 

Dec.  21,1922.... 

663.0 

40 

9.4 

22 

13.4 

75.4 

.84 

10,600 

8,000 

1,690 

ii 

Dec.  26,1922.... 

674.2 

40 

11.2 

26 

26.6 

66.3 

.86 

9,200 

6,800 

1,450 

I 

Dec.  29,1922.... 

676.2 

38 

6.6 

15 

6.4 

70.2 

.84 

9,900 

7,300 

1,560 

ii 

Jan.  16,1923  4... 

689.2 

40 

11.8 

29 

27.8 

64.0 

.85 

8,900 

6,500 

1,390 

hi 

Maintenance;  9  kg. 

hay:6 

Apr.  3,  1923 _ 

705.6 

6  32 

9.6 

21 

23.1 

67.5 

.89 

9,100 

6,400 

1,400 

hi 

Apr.  11,1923.... 

705.8 

37 

6.4 

14 

17.9 

68.9 

.83 

9.S00 

6,900 

1,500 

ii 

Apr.  18,  1923 _ 

704.2 

8  38 

8.2 

18 

22.1 

69.7 

.73 

11,000 

7,800 

1,690 

ii 

Apr.  24,1923.... 

700.8 

•32 

6.0 

12 

16.5 

71.4 

.78 

10,700 

7,600 

1,650 

i 

Submaintenance;  4.5 

kg.  hay:7 

May  5,1923.... 

669.0 

36 

7.2 

22 

25.5 

55.7 

.72 

8,900 

6,700 

1,410 

hi 

May  11,1923.... 

664.2 

38 

4.4 

16 

20.5 

65.1 

.79 

9,600 

7,200 

1,530 

hi 

May  18,1923.... 

662.2 

32 

5.2 

18 

21.5 

54.8 

.77 

8,300 

6,300 

1,330 

hi 

May  24,  1924. . .  . 

655.2 

32 

4.4 

17 

23.5 

56.1 

.76 

8,600 

6,600 

1,380 

ii 

Maintenance;  8  kg. 

hay:8 

June  18,  1923. . .  . 

642.8 

•60 

7.4 

20 

25.9 

86.3 

.79 

12,800 

10,000 

2,080 

hi 

June  23,  1923. . . . 
Maintenance;  9  kg. 

649.2 

•46 

23 

27.4 

85.5 

.89 

11,500 

8,900 

1,860 

ii 

hay:2 

Nov.  28,1923.... 
Dec.  6,1923.... 
Dec.  13,1923.... 
Dec.  20,  1923. . . . 
Submaintenance;  4.5 

(690.6) 

690.6 

690.6 

693.2 

44 

10 

22.3 

72.8 

.87 

10,000 

7,200 

1,550 

ii 

40 

13 

20.3 

76.9 

.91 

10,200 

7,400 

1,580 

ii 

36 

ca.  9 

23.2 

77.3 

.94 

10,000 

7,200 

1,550 

ii 

38 

3 

19.5 

57.2 

.90 

7,600 

5,500 

1,180 

ii 

kg.  hay:2 

Jan.  3,  1924. . . . 
Jan.  11,1924.... 
Jan.  18,1924.... 
Jan.  24,1924.... 
Jan.  31,1924.... 
Feb.  7,1924.... 

(650.0) 

650.4 
655.0 

655.4 

646.4 
629.2 

38 

36 

3 

14.0 

60.4 

.81 

8,800 

6,800 

1,420 

ii 

7 

10.1 

51.1 

.83 

7,300 

5,600 

1,180 

i 

36 

7 

11.9 

55.6 

.82 

8,000 

6,100 

1,290 

i 

36 

1 

9.0 

59.1 

.80 

8,700 

6,600 

1,400 

ii 

38 

14.5 

56.4 

.79 

8,400 

6,500 

1,360 

ii 

34 

ca.  1 

9.3 

52.5 

.80 

7,700 

6,100 

1,270 

ii 

Feb.  25,1924.... 
Maintenance;  7  kg. 

631.4 

34 

13.8 

53.4 

.84 

7,500 

5,900 

1,230 

i 

hay:10 

Nov.  26,  1924... 

744.6 

11  44 

1 . 

18.8 

73.0 

.85 

10,200 

6,800 

1,510 

i 

1 

1  No  meal  given  before  experiments  of  Dec.  17  and  Dec.  22. 

2  Steer  had  received  this  feed  daily  for  at  least  2  weeks  preceding  the  experimental  series.  *  Steer  was  eating. 

4  This  experiment  was  preceded  by  a  3-day  fast  on  Jan.  3  to  6. 

5  The  first  experiment  in  this  series  was  preceded  by  5  days  on  9  kg.  hay;  before  that  9  kg.  hay  and  2  kg. 

meal  were  given  daily.  •  Steer  was  lying  down. 

7  The  first  experiment  in  this  series  was  preceded  by  9  days  on  4.5  kg.  hay;  before  that  9  kg.  hay  were  given 

*  The  first  experiment  in  this  series  was  preceded  by  9  days  on  about  8  kg.  hay;  for  3  days  before  that  3 
to  6  kg.  hay  and  1  to  2  kg.  meal  were  given  daily.  •  Steer  had  just  stood  up. 

h  The  experiment  of  Nov.  26,  1924,  was  preceded  by  4  days  on  7  kg.  hay  daily;  before  that  8  kg.  hay  were 
given  daily  and  2  to  8  kg.  meal  on  some  days.  11  Heart-rate  on  Nov.  25. 


THE  STANDARD  METABOLISM  OF  STEERS  227 


Table  56. — Standard  metabolism  of  steer  D  at  different  levels  of  nutrition 


Heart- 

rate 

per 

min¬ 

ute 

In¬ 

sensi¬ 

ble 

loss 

per 

24 

hours 

Stall 

tem¬ 

pera¬ 

ture 

Aver¬ 

age 

cham¬ 

ber 

tem¬ 

pera¬ 

ture 

Car¬ 

bon 

Res- 

Heat  produced  per 

24  hours 

Feed-level, 
and  dates 

Live 

weight 

oxide 

pro¬ 

duced 

per 

half 

hour 

pira- 

tory 

quo¬ 

tient 

Total 

Per 

500  kg. 

Per 
sq.  m. 

Ac¬ 

tivity 

Realimentation;  3  to  8 

kg.  hay,  2  kg.  meal:1 

kg. 

kg. 

°C. 

°C. 

gm. 

cal. 

cal. 

cal. 

ii 

Dec.  17,1921.... 

584.4 

40 

6.8 

21 

22.3 

59.7 

(0.82) 

8,600 

7,400 

1,490 

Dec.  22,1921.... 

590.6 

40 

3.6 

7 

17.2 

58.2 

(.82) 

8,400 

7,100 

1,440 

ii 

Jan.  23,  1922. . .  . 

590.6 

3  40 

6.2 

12 

23.6 

67.3 

(.82) 

9,700 

8,200 

1,700 

ii 

Jan.  31,1922.... 

600.2 

48 

22 

21.0 

81.5 

(.82) 

11,700 

9,700 

1,990 

in 

Maintenance;  9  kg. 
hay:3 

ii 

Mar.  21,  1922 _ 

611.2 

4  56 

24.9 

86.3 

(.82) 

(.82) 

12,400 

10,100 

2,080 

Mar.  31,  1922.... 

612.6 

40 

6.8 

20 

22.8 

73.7 

10,600 

8,700 

1,780 

ii 

Realimentation;  4  to  9 
kg.  hay: 

1,860 

ii 

May  9,1922.... 

570.8 

46 

5.6 

18 

22.4 

73.9 

(.82) 

10,600 

9,300 

Maintenance;  9  kg. 
hay,  2  kg.  meal:3 

ii 

Dec.  15,1922.... 

675.6 

44 

13.0 

27 

26.0 

69.8 

.73 

11,000 

8,100 

1,740 

Dec.  19,1922.... 

670.8 

40 

11.8 

23 

10.5 

80.2 

.84 

11,300 

8,400 

1,790 

ii 

Dec.  30,1922.... 

677.2 

46 

17.6 

13 

8.2 

76.3 

.82 

11,000 

8,100 

1,730 

i 

Jan.  3,  1923. . .  . 

676.0 

48 

6.2 

11 

8.4 

76.8 

.82 

11,000 

8,100 

1,730 

i 

Maintenance;  9  kg. 
hay:8 

hi 

Apr.  4,1923.... 

697.8 

8  46 

6.6 

18 

21.8 

80.7 

.78 

12,100 

8,700 

1,870 

Apr.  12,1923.... 

699.2 

3  46 

7.8 

14 

18.9 

78.3 

.83 

11,200 

8,000 

1,730 

ii 

Apr.  19,1923.... 

693.0 

3  42 

6.4 

14 

20.9 

75.0 

.76 

11,500 

8,300 

1,780 

ii 

Apr.  25,1923.... 

693.0 

3  36 

9.0 

20 

23.6 

77.3 

.86 

10,700 

7,700 

1,660 

Submaintenance;  4.5 
kg.  hay:7 

hi 

May  4,1923.... 

672.0 

48 

5.8 

21 

24.2 

67.1 

.72 

10,700 

8,000 

1,690 

May  12,1923.... 

659.6 

8  60 

8.2 

24 

26.8 

66.6 

.74 

10,400 

7,900 

1,660 

hi 

May  19,1923.... 

651.2 

48 

5.6 

21 

24.8 

67.1 

.73 

10,600 

8,100 

1,710 

hi 

May  25,  1923. . .  . 

649.0 

48 

6.2 

22 

27.1 

68.0 

.73 

10,700 

8,200 

1,730 

m 

June  1,1923.... 

640.8 

40 

7.2 

19 

23.6 

66.3 

.74 

10,300 

8,000 

1,680 

in 

June  8,  1923. . .  . 

633.8 

48 

4.2 

18 

21.6 

68.1 

.78 

10,200 

8,000 

1,670 

ii 

Maintenance;  9  kg. 
hay:* 

1,960 

June  16,  1923. . .  . 

659.0 

60 

9.4 

18 

24.6 

86.4 

.84 

12,200 

9,300 

I 

June  22,  1923 .... 

660.0 

48 

12.2 

26 

28.8 

82.6 

.85 

11,500 

8,700 

1,840 

hi 

Maintenance;  9  kg. 
hay:8 

hi 

Nov.  30,  1923... . 

683.4 

48 

9 

19.8 

85.2 

.86 

11,800 

8,600 

1,850 

Dec.  7,1923.... 

673.6 

52 

13 

21.6 

87.4 

.91 

11,600 

8,600 

1,830 

in 

Dec.  14,1923.... 

674.0 

44 

11 

18.6 

79.9 

.89 

10,800 

8,000 

1,700 

hi 

Dec.  21,1923.... 

686.8 

44 

8 

18.4 

79.6 

.84 

11,200 

8,200 

1,750 

hi 

Submaintenance;  4.5 
kg.  hay:8 

1,580 

ii 

Jan.  4,  1924. . .  . 

653.2 

36 

5 

10.6 

67.3 

.81 

9,800 

7,500 

Jan.  12,1924.... 

633.6 

40 

9 

11.0 

60.6 

.80 

8,900 

7,000 

1,460 

i 

Jan.  19,1924.... 
Jan.  25,1924.... 

639.6 

644.2 

44 

4 

10.7 

69.3 

.82 

10,000 

7,800 

1,630 

i 

48 

5 

10.1 

61.9 

.78 

9,300 

7,200 

1,510 

i 

Feb.  1,1924.... 

627.4 

42 

5 

6.3 

65.8 

.79 

9,700 

7,700 

1,600 

ii 

Feb.  8,1924.... 

620.6 

56 

-6 

8.9 

57.6 

.79 

8,500 

6,800 

1,410 

ii 

Feb.  26,1924.... 
Maintenance;  7  kg. 

614.6 

42 

-2 

11.1 

64.8 

.78 

9,700 

7,900 

1,620 

i 

hay:10 

1,830 

Nov.  26,  1924... . 

715.2 

11  52 

17.5 

81.6 

.80 

12,000 

8,400 

i 

1  No  meal  given  before  experiment  of  Dec.  17  and  Dec.  22.  1  Steer  was  lying  down. 

*  Steer  had  received  this  feed  daily  for  at  least  2  weeks  preceding  the  experimental  series.  4  Steer  was  eating. 

*  The  first  experiment  in  this  series  was  preceded  by  6  days  on  9  kg.  hay;  before  that  9  kg.  hay  and  2  kg. 

meal  were  given  daily.  8  Steer  was  ruminating. 

1  The  first  experiment  in  this  series  was  preceded  by  8  days  on  4.5  kg.  hay ;  before  that  9  kg.  hay  were  given 
daily.  8  Steer  had  just  stood  up. 

*  The  first  experiment  in  this  series  was  preceded  by  7  days  on  9  kg.  hay;  before  that  4.5  kg.  hay  were 
given  daily . 

10  The  experiment  of  Nov.  26,  1924,  was  preceded  by  4  days  on  7  kg.  hay;  before  that  8  kg.  hay  were  given 
daily  and  2  to  8  kg.  meal  on  some  days.  11  Heart-rate  on  Nov.  25. 


228 


METABOLISM  OF  THE  FASTING  STEER 


part  pass  through  the  fatty-acid  stage  of  fermentation,  would  fall  in  line 
with  the  theory  that  the  stimulation  of  fatty  acids  accounts  for  the 
increased  heat-production  following  the  ingestion  of  food. 

It  is  clear  that  this  type  of  experiment  furnishes  the  basis  for  measuring 
the  influence  of  a  given  amount  of  food  upon  essentially  the  fasting 
katabolism  of  animals.  In  this  preliminary  discussion  of  this  feature  of 
the  experiments  we  have  not  given  all  the  attention  that  should  be  given, 
perhaps,  to  the  matter  of  computing  the  metabolism  to  a  standard  day 
of  standing  and  lying,  as  it  seemed  to  be  a  refinement  hardly  justified  at 
the  present  stage.  Further  study  of  standard  foodstuffs,  with  this  type 
of  experimentation,  are  now  under  investigation. 

The  Standard  Metabolism  of  Steers  under  Different  Conditions 

In  order  to  determine  the  metabolic  plane  upon  which  the  steer  was 
living  at  the  time  of  beginning  a  fast  and  to  note  the  rapidity  of  recovery 
after  fasting,  a  number  of  standard  metabolism  experiments  were  made 
with  each  of  our  four  animals.  As  outlined  in  our  earlier  study  of  under- 
nutrition  in  steers,0  the  conditions  prerequisite  for  the  measurement  of 
the  standard  metabolism  are  that  the  animal  should  be  standing  quietly 
and  should  have  been  without  food  for  24  hours.  Under  these  conditions 
the  standard  metabolism  has  been  measured  in  four  half-hour  periods  and 
computed  to  the  24-hour  basis.  Numerous  metabolism  experiments  of 
this  type  were  made  during  the  feeding-periods  between  the  fasts,  the  data 
for  which  have  been  summarized  in  Tables  55,  56,  and  57,  for  steers  C,  D, 
and  E  and  F,  respectively.  The  measurements  secured  on  the  first  day 
of  each  of  the  fasts  of  5  to  14  days  and  on  the  first  day  of  each  of  the 
2-day  fasts  in  1923  were  also  made  under  standard  conditions,  and  although 
not  included  in  these  tables,  should  be  taken  into  consideration  in  this 
discussion.  (See  Tables  44,  45,  and  46,  pp.  166,  168,  and  169.) 

At  the  start  it  was  intended  to  make  these  measurements  at  a  chamber 
temperature  of  not  far  from  20°  C.  Subsequently  it  seemed  desirable  to 
study  also  the  influence  of  different  environmental  temperatures.  A  few 
standard  metabolism  experiments  were  accordingly  made  at  temperatures 
markedly  lower  or  higher  than  20°  C.  In  addition,  in  order  to  obtain 
further  information  regarding  the  influence  of  maintenance  and  submainte¬ 
nance  rations,  a  series  of  standard  metabolism  experiments  were  made  at 
these  two  nutritive  levels.  It  is  thus  possible  to  note  whether  the  new 
findings  confirm  the  earlier  results  obtained  with  our  first  groups  of  steers 
subjected  to  prolonged  undernutrition.  Since  steers  E  and  F  were  younger 
than  steers  C  and  D,  it  is  also  possible  to  make  comparisons  of  the  influence 
of  age. 

Factors  Other  than  the  Nutritive  Level  which  Affect  the  Standard  Metabolism 

The  comparison  of  the  different  experiments  may  best  be  made  by  con¬ 
sidering  the  heat-production  per  500  kg.  of  body-weight  or  per  square 
meter  of  body-surface,  although  on  either  of  these  two  bases  there  are 


°  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  197. 


THE  STANDARD  METABOLISM  OF  STEERS 


229 


wide  differences  in  the  results.  In  the  series  of  standard  metabolism 
experiments  with  steer  C,  for  example,  the  heat-production  per  500  kg. 
of  body-weight  ranges  from  a  minimum  of  5,500  to  a  maximum  of  10,100 
calories,  i.  e.,  a  range  of  84  per  cent.  Similarly,  on  the  basis  of  the  heat- 
production  per  square  meter  of  body-surface,  there  is  a  difference  of  76 
per  cent  between  the  minimum  value  of  1,180  calories  and  the  maximum 
value  of  2,080  calories.  These  differences  can  be  studied  intelligently 
only  by  taking  account  of  the  various  factors  which  affect  the  metabolism. 
Presumably,  differences  in  body-weight  are  ruled  out  by  the  computation 
on  the  basis  of  per  square  meter  of  body-surface.  Age  probably  does  not 
play  any  great  role  in  the  comparison  of  the  results  obtained  with  steers 
C  and  D  (although  their  experiments  cover  a  3-year  period  from  December 
17,  1921,  to  November  26,  1924),  as  they  were  3*4  years  old  at  the  start. 
Age  does  play  a  role  if  the  data  for  steers  E  and  F  are  compared  with 
those  for  steers  C  and  D,  since  steers  E  and  F  were  yearlings.  If  steers 
E  and  F  are  considered  alone,  the  factor  of  age  does  not  affect  the  com¬ 
parison,  since  the  standard  metabolism  experiments  with  steers  E  and  F 
cover  a  period  of  only  3  months.  Environmental  temperature  undoubtedly 
plays  a  role,  for  the  animals  were  purposely  studied  at  different  tempera¬ 
tures.  The  temperature  to  which  the  animal  was  exposed  prior  to  and 
during  the  test  must  therefore  be  carefully  considered. 

Another  factor  which  must  not  be  overlooked  is  the  variability  in 
activity.  Although  the  steers  soon  became  accustomed  to  the  respiration 
chamber  and  the  experimental  technique,  there  were  certain  roughly  meas¬ 
urable  differences  in  their  activity  in  the  stall,  due  to  differences  in  indi¬ 
viduality.  As  shown  in  our  earlier  publication,®  the  maximum  stall 
activity  rarely  results  in  an  increase  in  metabolism  of  more  than  15  per 
cent  on  the  average.  There  were  no  instances  of  excessive  stall  activity 
during  these  standard  metabolism  experiments,  however.  In  accordance 
with  our  conventional  method  of  estimating  the  activity  from  the  kymo¬ 
graph  records,  we  have  indicated  in  Tables  55,  56,  and  57  whether  the  stall 
activity  inside  the  respiration  chamber  was  I,  II,  or  III.  Activity  I  repre¬ 
sents  the  minimum  degree  of  movement  and  activity  III  the  greatest 
degree,  but  not  more  than  15  per  cent  greater  than  activity  I.  Even 
activity  III,  however,  does  not  involve  a  degree  of  activity  sufficient  to 
vitiate  an  experiment,  although  it  is  perceptibly  greater  than  activity  I. 
As  can  be  seen  from  many  of  these  experiments,  in  which  the  activities  are 
different  but  the  other  factors  are  essentially  constant,  there  is  not  a  great 
difference  in  the  metabolism  on  those  days  when  the  activity  varies  from 
I  to  III.  A  typical  instance  is  the  comparison  of  the  experiments  of 
December  26,  1922,  and  January  16,  1923,  with  steer  C.  In  both  experi¬ 
ments  the  feed-level  and  the  environmental  temperature  were  the  same. 
Activity  I  prevailed  during  the  experiment  on  December  26  and  activity 
III  on  January  16,  and  yet  the  heat-production  per  square  meter  of  body- 
surface  was  1,450  calories  in  the  first  case  and  1,390  calories  in  the  second 
case.  Differences  in  activity  should  not,  however,  be  wholly  disregarded. 


°  Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  209. 


230 


METABOLISM  OF  THE  FASTING  STEER 


Level  of  the  Standard  Metabolism  at  the  Beginning  of  the  Different  Fasts 

In  general,  the  standard  metabolism  of  steers  C  and  D  was  unusually 
high  on  the  first  day  of  the  different  fasts,  save  in  the  fast  following 
submaintenance  feeding.  Indeed,  although  the  extreme  range  in  the  values 
for  the  first  day  of  fasting  is  not  any  greater  than  the  range  noted  in  Tables 
55  and  56,  actually  the  highest  values  are  found  with  both  steers  at  the 
beginning  of  the  fasts.  Thus,  in  Table  50,  page  178,  it  can  be  seen  that 
the  highest  value  for  steer  C,  2,090  calories  per  square  meter  of  body- 
surface  on  the  first  day  of  the  fast  in  November  1922,  is  actually  somewhat 
higher  than  the  highest  value,  2,080  calories,  recorded  in  Table  55.  With 
steer  D  the  highest  initial  value  in  any  of  the  long  fasts  is  2,490  calories 
on  the  first  day  of  the  fast  in  November  1923,  and  the  highest  value 
recorded  in  Table  56  is  2,080  calories.  These  high  values  at  the  beginning 
of  the  fasts  are  in  part  to  be  explained  on  the  ground  that  an  effort  was 
made,  although  perhaps  only  partly  successful,  to  bring  these  animals  by 
feeding  to  a  somewhat  higher  nutritive  plane,  i.  e.,  to  at  least  maintenance, 
if  not  above,  preparatory  to  withstanding  the  fast.  This  effort  is  undoubt¬ 
edly  reflected  in  general  in  these  somewhat  higher  values  noted  on  the 
first  day  of  fasting. 

Influence  of  Environmental  Temperature  Upon  Standard  Metabolism 

In  certain  of  these  standard  metabolism  experiments  the  variation  in 
temperature  was  such  as  to  make  comparisons  of  the  influence  of  the 
different  temperatures  justifiable,  for  the  other  factors  were  held  sufficiently 
constant  to  consider  that  the  temperature  factor  may  be  the  determining 
cause  of  any  change  noted  in  the  metabolism.  The  temperature  effect  alone 
will  therefore  be  considered  at  this  point.  With  steer  C  on  December  29, 
1922,  at  a  chamber  temperature  of  6.4°  C.  the  metabolism  per  square  meter 
of  body-surface  was  1,560  calories  per  24  hours.  The  day  before  the 
temperature  was  26.6°  C.  and  the  metabolism  was  1,450  calories.  On 
January  16,  1923,  the  temperature  was  27.8°  C.  and  the  metabolism  was 
1,390  calories.  Thus,  seemingly  the  lower  temperature  has  increased  the 
metabolism  slightly,  the  increase  being  about  100  calories  per  square  meter 
of  body-surface  with  a  lowering  in  temperature  of  about  20°  C.  With 
steer  D  on  December  15,  1922,  at  a  chamber  temperature  of  26°  C.  the 
heat-production  was  1,740  calories  per  square  meter  of  body-surface,  and 
on  December  30,  1922,  at  a  chamber  temperature  of  8.2°  C.  it  was  1,730 
calories,  or  practically  identical  with  the  value  obtained  at  the  higher 
temperature. 

In  this  study  it  is  of  interest  to  compare  the  series  of  submaintenance 
experiments  with  steer  D  from  January  4  to  February  26,  1924,  with  the 
submaintenance  series  from  May  4  to  June  8,  1923.  The  body-weight  was 
about  the  same  in  both  cases.  The  environmental  temperature  was  much 
higher  in  the  spring  series  than  in  the  winter  series.  The  ration  was 
exactly  the  same,  but  the  stall  activity  was  in  general  a  little  higher  in 
the  spring.  The  heat-production  per  square  meter  of  body-surface  is 
perceptibly  higher  in  the  spring  series,  i.  e-,  about  1,690  calories  as  compared 
with  1,540  calories  in  the  winter  series.  The  average  chamber  temperature 


THE  STANDARD  METABOLISM  OF  STEERS 


231 


was  about  24°  C.  in  the  spring  and  about  10°  C.  in  the  winter.  A  similar 
comparison  of  the  data  for  steer  C  shows  the  same  effect,  although  it  is 
a  little  less  striking. 

This  evidence  tends  to  support  our  earlier  suggestion  made  in  connection 
with  the  undernutrition  studies,®  that  the  lower  environmental  temperature 
frequently  may  be  accompanied  by  a  lower  heat-production.  There  are  two 
contaminating  features  in  this  evidence,  however.  In  the  first  place,  the 
activity  with  both  animals  was  slightly  higher  in  the  spring  series,  although, 
judging  from  our  kymograph  records  of  the  activity  of  the  animals  when 
inside  the  respiration  chamber,  it  would  seem  as  if  the  difference  in  the 
heat-production  due  to  a  difference  in  activity  could  hardly  be  more  than 
15  per  cent.  If  one  reduced  by  15  per  cent  the  average  value  noted  in  the 
spring  series,  the  average  heat-production  would  be  1,440  calories  as  com¬ 
pared  with  the  average  value  of  1,540  calories  noted  in  the  winter  series 
of  1924.  On  this  basis  the  lower  temperature  is  accompanied  by  a  higher 
and  not  by  a  lower  metabolism.  This  is  a  finding  fully  in  line  with  the 
conclusion  drawn  from  the  analysis  of  the  data  obtained  in  the  4-day 
respiration  experiments  with  steers  E  and  F  when  on  submaintenance  rations 
(see  p.  200).  It  should  be  pointed  out,  however,  that  the  study  of  the* 
influence  of  environmental  temperature  made  during  the  4-day  respiration 
experiments  of  steers  E  and  F  is  based  upon  data  obtained  during  one 
season  only  of  the  year  and  that  the  study  of  the  influence  of  environmental 
temperature  in  the  experiments  in  the  spring  of  1923  and  the  winter  of  1924 
involves  the  possible  effect  of  changes  in  season  upon  the  metabolism.  This 
factor  has  not  as  yet  been  thoroughly  studied.  If  we  disregard  for  the 
moment,  however,  any  possible  seasonal  variation  in  metabolism,  the  correc¬ 
tion  of  the  heat-production  in  the  spring  series  of  1923  for  the  difference  in 
activity  brings  out  the  fact  that  an  average  difference  in  temperature  of 
about  14°  C.  made  but  a  difference  of  100  calories  or  7  per  cent  in  the  heat- 
production  per  square  meter  of  body-surface.  It  is  obvious  from  this  par¬ 
ticular  comparison  that  the  temperature  effect  is  much  less  with  these  large 
ruminants  than  one  finds  in  the  reported  observations  on  other  animals, 
although  the  influence  of  activity  and  shivering  has  too  frequently  been 
entirely  overlooked  in  experiments  with  smaller  animals. 

Influence  of  Level  of  Nutrition  Upon  the  Standard  Metabolism 

A  comparison  of  the  standard  metabolism  at  the  maintenance  and  sub¬ 
maintenance  levels  of  nutrition  shows  that  with  steer  C  the  heat-production 
per  square  meter  of  body-surface  per  24  hours  was  not  far  from  1,600 
calories  when  he  was  receiving  maintenance  rations  and  that  it  was  per¬ 
ceptibly  lower  in  the  two  series  of  submaintenance  experiments.  This 
finding  confirms  our  earlier  finding  on  the  effect  of  submaintenance  feeding. 
With  steer  D  the  situation  is  by  no  means  so  clear.  The  metabolism  of 
this  animal  with  full  maintenance  rations  is  perceptibly  higher  than  that 
of  steer  C,  averaging  more  nearly  1,800  calories  per  square  meter  of  body- 
surface.  On  submaintenance  rations  the  fall  in  metabolism  is  only  to 
about  1,700  calories  in  the  first  submaintenance  series,  that  is,  from  May  4 


“Benedict  and  Ritzman,  Carnegie  Inst.  Wash.  Pub.  No.  324,  1923,  p.  219. 


232 


METABOLISM  OF  THE  FASTING  STEER 


to  June  8,  1923,  although  in  the  series  from  January  4  to  February  26, 
1924,  the  fall  is  much  more  pronounced.  In  general,  however,  the  data 
for  both  animals  support  the  general  contention  that  submaintenance 
feeding  lowers  the  metabolism  perceptibly. 

Table  57 .—Standard  metabolism  of  steers  E  and  F  at  different  levels  of  nutrition 


Heart- 

rate 

per 

min¬ 

ute 

In- 

Aver- 

Car¬ 

bon 

di¬ 

oxide 

pro¬ 

duced 

per 

half 

hour 

Heat  produced  per 

24  hours 

Steer,  feed-level, 
and  dates 

Live 

weight 

Tie' 

loss 

per 

24 

hours 

Stall 

tem¬ 

pera¬ 

ture 

cham¬ 

ber 

tem¬ 

pera¬ 

ture 

pira- 

tory 

quo¬ 

tient 

Total 

Per 

500  kg. 

Per 
sq.  m. 

Ac¬ 

tivity 

Steer  E: 

Maintenance;  5  kg. 
hay;  0.68  kg.  meal1 — 
Nov.  26,  1923.. 

kg. 

264.8 

52 

kg. 

6.4 

°C. 

16 

°C. 

21.3 

gm. 

50.9 

0.87 

cal. 

7,000 

cal. 

13,200 

cal. 

1,980 

hi 

Dec.  3,1923.. 

266 .4 

56 

5.8 

15 

20.0 

48.3 

.84 

6,800 

12,800 

1,920 

hi 

Dec.  10,1923.. 

268.8 

44 

6.6 

20 

23.0 

45.8 

.85 

6,400 

11,900 

1,790 

hi 

Dec.  17,1923.. 

270.6 

48 

7.0 

14 

18.8 

48.3 

.85 

6,800 

12,600 

1,890 

hi 

Submaintenance;  2.5 
kg.  hay;  0.30  kg. 
meal2 — 

Dec.  28,1923.. 

260.0 

36 

4.6 

15 

15.7 

35.8 

.80 

5,300 

10,200 

1,520 

ii 

Dec.  31,1923.. 

258.0 

36 

3.2 

14 

13.8 

36.4 

.78 

5,400 

10,500 

1,560 

ii 

Jan.  8,1924.. 

255.2 

36 

2.4 

15 

17.2 

36.2 

.78 

5,400 

10,600 

1,570 

ii 

Jan.  14,1924.. 

256.2 

38 

2.6 

15.7 

38.4 

.77 

5,800 

11,300 

1,680 

i 

Jan.  21,1924.. 

253.6 

44 

3.6 

11 

8.4 

45.5 

.76 

7,000 

13,800 

2,030 

Jan.  28,1924.. 

252.6 

44 

3.0 

11 

15.0 

40.7 

.77 

6,200 

12,300 

1,810 

i 

Submaintenance;  2.5 
kg.  hay;  0.10  kg. 
meal3 — 

Feb.  4,1924.. 

251.0 

38 

2.4 

15 

17.6 

38.6 

.81 

5,600 

11,200 

1,640 

ii 

Realimentation4 * — 
Feb.  18,1924.. 

237.2 

‘52 

1.2 

17 

15.1 

34.1 

.76 

5,200 

11,000 

1,580 

i 

Steer  F: 

Maintenance;  5  kg. 
hay;  0.68  kg. 
meal 1 — 

Nov.  27,  1923.. 

290.0 

60 

5.4 

18 

21.8 

50.9 

.85 

7,100 

12,200 

1,900 

ii 

Dec.  4,1923.. 

293.0 

44 

5.4 

16 

20.5 

52.2 

.85 

7,300 

12,500 

1,940 

hi 

Dec.  11,1923.. 

296.0 

52 

8.0 

18 

22.2 

46.0 

.82 

6,600 

11,200 

1,740 

hi 

Dec.  18,1923.. 

298.0 

42 

4.0 

10 

15.1 

48.2 

.84 

6,800 

11,400 

1,790 

hi 

Submaintenance;  2.5 
kg.  hay;  0.30  kg. 
meal2 — 

Dec.  29,1923.. 

285.6 

38 

3.4 

16 

20.3 

45.2 

.80 

6,600 

11,600 

1,780 

ii 

Jan.  2,1924.. 

284.8 

42 

3.2 

12 

15.6 

41.5 

.77 

6,300 

11,100 

1,700 

ii 

Jan.  9,1924.. 

280.6 

42 

2.8 

16 

16.7 

39.6 

.79 

5,900 

10,500 

1,610 

i 

Jan.  17,1924.. 

279.2 

42 

3.4 

18 

22.7 

46.4 

.81 

6,700 

12,000 

1,840 

i 

Jan.  22,1924.. 

278.8 

38 

2.6 

13 

20.6 

44.8 

.79 

6,600 

12,000 

1,810 

i 

Submaintenance;  2.5 
kg.  hay;  0.10  kg. 
meal 3 — 

Jan.  29,1924.. 

276.4 

36 

3.2 

18 

21.0 

46.4 

.79 

6,900 

12,500 

1,900 

hi 

Feb.  5,1924.. 

272.8 

40 

3.0 

17 

16.1 

42.9 

.78 

6,400 

11,700 

1,780 

ii 

Realimentation  6 — 
Feb.  19,1924.. 

260.6 

‘  64 

1.8 

16 

16.3 

34.4 

.73 

5,400 

10,400 

1,540 

i 

1  The  period  of  maintenance  feeding  began  on  Nov.  19,  1923. 

1  The  period  of  submaintenance  feeding  began  on  the  afternoon  of  Dec.  17,  1923. 

*  The  period  of  lower  submaintenance  feeding  began  on  the  afternoon  of  Jan.  28,  1924. 

«  The  experiment  on  Feb.  18,  1924,  was  made  24  hours  after  the  5-day  fast  of  Feb.  12  to  17.  The  steer  had  con 

Burned  1.75  kg.  hay  and  500  gm.  meal  at  the  end  of  the  fast,  or  24  hours  before  this  experiment. 

3  Steer  had  just  stood  up. 

•  The  experiment  on  Feb.  19,  1924,  was  made  24  hours  after  the  6-day  fast  of  Feb.  12  to  18.  The  Bteer  had  con 

Burned  1.45  kg.  hay  and  500  gm.  meal  at  the  end  of  the  fast,  or  24  hours  before  this  experiment. 


THE  STANDARD  METABOLISM  OF  STEERS 


233 


In  considering  the  standard  metabolism  of  steers  E  and  F,  and  particu¬ 
larly  the  influence  of  a  marked  curtailment  in  ration,  it  must  be  borne  in 
mind  that  in  the  series  of  experiments  reported  in  Table  57  these  animals 
were  just  a  little  over  a  year  old.  In  the  series  of  4-day  experiments  from 
December  1924  to  May  1925,  however,  in  which  the  influence  of  sub- 
maintenance  feeding  was  also  studied  (see  Table  53,  p.  195),  they  were 
practically  a  year  older,  or  about  21/2  years  old.  According  to  the  standard 
metabolism  measurements  reported  in  Table  57,  the  curtailment  in  ration 
resulted  at  first  in  a  material  fall  in  the  metabolism  of  steer  E,  which 
persisted  for  the  three  days,  December  28,  December  31,  and  January  8. 
There  was  then  a  tendency  for  the  metabolism  to  rise  during  the  rest  of 
the  month.  Prior  to  the  curtailment  in  ration,  the  heat-production  per 
square  meter  of  body-surface  was  approximately  1,900  calories  on  the 
average,  and  during  the  submaintenance  period  it  was  not  far  from  1,700 
calories,  i.  e.,  there  was  no  appreciable  change  in  the  metabolism.  Simi¬ 
larly  with  steer  F,  the  average  heat-production  prior  to  submaintenance 
feeding  was  about  1,800  calories  and  during  the  entire  submaintenance 
period  it  was  not  far  from  the  same.  It  would  appear,  therefore,  as  if 
the  metabolism  of  these  young  animals  did  not  react  to  the  submaintenance 
regime  as  in  the  case  of  the  older  animals,  probably  because  a  strong  effort 
to  continue  growing  persisted  at  this  age. 

Complications  arise,  however,  in  making  strict  comparisons  in  that  the 
temperature  factor  undoubtedly  enters  into  certain  of  these  experiments. 
Thus,  the  high  heat-production  of  2,030  calories  per  square  meter  of  body- 
surface  with  steer  E  on  January  21,  1924  (see  Table  57),  may  be  in  part 
accounted  for  by  the  fact  that  the  chamber  temperature  was  but  8.4°  C. 
When  these  animals,  E  and  F,  were  studied  a  year  later,  however,  in  the 
4-day  experiments  (see  Table  53,  p.  195),  there  was  an  almost  immediate 
response  in  the  metabolism  to  the  submaintenance  feeding,  in  spite  of  the 
fact  that  prior  to  the  respiration  experiment  the  submaintenance  ration 
had  been  fed  at  the  most  for  but  three  weeks.  Here,  again,  the  pronounced 
changes  in  environmental  temperature  play  somewhat  of  a  role,  and  com¬ 
parisons  of  the  various  days  can  be  made  only  when  the  environmental 
temperature  is  taken  into  consideration.  Yet  it  is  clear  that  at  the  age  of 
2 V2  years  these  animals  reacted  strikingly  to  a  3  weeks’  period  of  lowered 
food  intake,  in  that  the  metabolism  was  distinctly  depressed. 

Steers  C  and  D  show  an  almost  immediate  response  in  metabolism  to 
the  lower  feed-level.  In  none  of  the  experiments  with  steers  C,  D,  E,  and 
F  was  the  submaintenance  regime  carried  far  enough  to  note  how  long 
the  low  plateau  would  be  held.  Judging  from  the  two  submaintenance 
series  in  May  1923,  and  in  January  and  February  1924,  there  was  no  dis¬ 
position  for  the  metabolism  per  square  meter  of  body-surface  to  decrease 
materially  in  the  length  of  time  covered  by  these  submaintenance  periods. 

Although  the  analysis  of  the  standard  metabolism  of  these  steers  is 
complicated  by  the  influence  of  factors  such  as  environmental  temperature, 
the  amount  and  character  of  the  previous  feed,  and  the  age  of  the  animal, 
the  most  directly  comparable  experiments  show  clearly  that  adult  animals 
which  have  been  upon  full  feed  and  are  presumably  in  a  maintenance 


234 


METABOLISM  OF  THE  FASTING  STEER 


condition,  respond  definitely  to  a  submaintenance  ration  in  that  they  have 
a  persistently  low  metabolism.  The  two  young  animals,  when  1  year 
old,  did  not  react  so  rapidly  to  curtailed  rations,  but  at  the  age  of  2V2 
years  the  substitution  of  a  submaintenance  ration  in  place  of  the  mainte¬ 
nance  ration  resulted  in  a  distinctly  lower  metabolism,  even  when  the 
submaintenance  regime  had  prevailed  for  only  three  weeks. 

This  particular  feature  of  the  rapidity  of  onset  of  a  low  metabolism 
following  submaintenance  rations  constitutes,  we  believe,  the  danger  in 
attempting  to  estimate  the  fasting  katabolism  of  steers  by  the  method 
of  studying  the  metabolism  of  an  animal  on  a  full  maintenance  ration  and 
then  on  a  submaintenance  ration,  when  the  submaintenance  ration  has  been 
given  for  a  period  of  three  weeks  or  more.  These  conditions  introduce 
not  only  the  effect  of  the  lowered  ingestion  of  food,  which  is  supposed  to 
be  studied,  but  the  depressing  effect  of  the  submaintenance  regime  upon 
the  basal  or  fasting  katabolism. 


SUMMARY 

(1)  Two  adult  steers,  C  and  D,  were  subjected  at  varying  intervals 
during  a  period  of  2%  years  to  7  different  fasts  of  from  5  to  14  days  in 
length.  Two  of  the  fasts  followed  pasture  feeding,  one  a  submaintenance 
ration  of  hay  alone,  and  the  rest  a  maintenance  ration  of  hay  and  meal.  The 
effects  of  intermittent  fasting  and  of  sudden  and  marked  changes  in  envi¬ 
ronmental  temperature  were  studied  in  a  further  series  of  fasts  of  2  and  3 
•days’  duration,  at  approximately  weekly  intervals.  Two  younger  and 
smaller  steers,  E  and  F,  fasted  for  5  or  6  days  following  submaintenance 
feeding.  The  gaseous  metabolism  measurements  in  all  these  fasts  were 
made  in  three  or  four  consecutive  half-hour  periods.  Subsequently  each 
animal  fasted  again,  and  the  gaseous  metabolism  was  measured  in  8-hour 
periods  during  three  consecutive  days.  A  number  of  continuous  4-day 
respiration  experiments  (2  days  on  feed  and  2  days  fasting)  were  made 
with  steers  E  and  F  when  they  were  about  2%  years  old,  in  which  the 
-effects  of  variations  in  the  amount  and  character  of  the  ration  and  of 
high  and  low  environmental  temperatures  were  studied. 

(2)  Great  irregularity  in  the  loss  in  weight  during  fasting  could  be 
explained,  as  during  the  feed  periods,  by  irregularity  in  the  intake  and 
outgo  of  visible  matter,  particularly  the  water  intake.  The  magnitude  of 
the  large  losses  during  the  first  few  days  was  influenced  by  the  pre-fasting 
feed-level.  The  losses  were  largest  in  the  fasts  following  pasture  feeding. 
In  the  fasts  following  maintenance  feeding  on  hay  and  meal  the  losses 
were  much  smaller,  and  in  those  which  followed  submaintenance  feeding 
they  were  still  smaller.  After  the  fourth  day  of  fasting  the  daily  losses 
in  live  weight  became  smaller  and  nearly  similar,  irrespective  of  the 
previous  ration  or  the  individual  animal.  It  is  concluded  that  two  animals 
of  the  same  size  and  age,  receiving  feed  similar  in  character  and  amount, 
are  fairly  close  physiological  duplicates  in  respect  to  the  loss  in  weight 
during  fasting.  The  loss  or  gain  in  live  weight  per  se,  however,  can  not 
be  accepted  as  an  index  of  change  in  body-tissue  without  taking  into 
consideration  other  factors,  particularly  the  consumption  of  water  and 
the  excretion  of  urine  and  feces. 

(3)  The  insensible  perspiration  from  day  to  day  was  reasonably  constant 
under  the  same  conditions  of  feeding,  particularly  if  the  environmental 
temperature  remained  unchanged.  Marked  changes  in  temperature,  how¬ 
ever,  were  often  accompanied  by  changes  in  the  insensible  perspiration  even 
at  the  same  feed-level,  a  large  insensible  loss  frequently  appearing  with  a 
high  temperature  and  vice  versa.  The  chief  factor  affecting  the  magnitude 
of  the  insensible  perspiration  was  the  amount  of  the  ration,  the  loss  being 
higher  with  heavy  feeding  than  with  light  feeding.  When  the  steer  had 
been  fasting  for  24  hours  there  was  usually  a  definite  decrease  in  the 
insensible  perspiration,  provided  the  temperature  remained  essentially 
unchanged.  On  the  second  day  there  was  a  still  greater  decrease.  After 
the  third  or  fourth  day  the  loss  remained  practically  constant  at  about 
3  or  4  kg.  per  day  in  the  fasts  following  maintenance  or  pasture  feeding 

235 


236 


METABOLISM  OF  THE  FASTING  STEER 


and  at  about  2.5  kg.  in  the  fasts  following  submaintenance  feeding.  With 
the  resumption  of  feeding  the  insensible  perspiration  increased. 

(4)  During  fasting  the  water  consumption  was  affected  by  changes  in 
the  environmental  temperature.  On  some  fasting  days  no  water  was  taken 
and  on  other  days  fairly  large  amounts  were  taken.  Steer  C,  when  fasting 
after  submaintenance  feeding,  drank  practically  no  water  for  9  days.  In 
other  fasts  the  animals  refused  water  for  periods  of  3  and  4  days.  In 
general,  less  water  was  consumed  in  the  fasts  following  submaintenance 
or  pasture  feeding  than  in  those  following  maintenance  feeding.  Water 
may  be  withheld  from  fasting  steers  without  detriment,  especially  if  the 
steers  have  previously  been  on  reduced  rations  or  on  pasture. 

(5)  The  daily  weight  of  fresh  feces  during  the  feed  periods  was  in  general 
twice  that  of  the  ration.  During  fasting  the  fecal  excretion  was  greatly 
reduced,  although  some  feces  were  passed  daily  throughout  the  entire  fast, 
irrespective  of  its  length.  On  the  first  day  there  was  usually  a  small 
decrease  in  the  weight  of  feces.  On  the  second  day  the  excretion  was 
somewhat  less  than  half  as  much  as  on  the  first  day,  save  in  the  fast  after 
submaintenance  feeding.  After  the  fifth  day  the  average  excretion  was 
about  1.5  kg.  per  day.  The  number  of  defecations  on  the  first  day  was 
less  in  the  fasts  following  pasture  or  submaintenance  feeding  than  in  those 
after  maintenance  feeding.  During  the  14-day  fast  the  number  of  defeca¬ 
tions  and  the  amount  of  each  defecation  gradually  decreased  until  about 
the  seventh  day,  after  which  there  were  a  large  number  of  small  defecations 
daily.  At  the  beginning  of  the  fast  the  feces  were  soft  and  plastic,  but 
as  the  quantity  decreased  during  the  fast  they  became  visibly  firmer,  being 
dry  and  pilular  by  the  fifth  day.  After  eight  days  their  consistency  was 
variable,  some  passages  being  firm  and  fibrous  and  others  soft.  The  feces 
were  exceedingly  offensive  in  odor  toward  the  end  of  the  fast.  The  per¬ 
centage  of  dry  matter  in  feces  increased  in  some  fasts  and  decreased  in 
others.  A  satisfactory  explanation  for  this  anomalous  situation  was  not 
found.  The  actual  weight  of  dry  matter  in  feces  decreased  rapidly  until, 
on  the  fifth  day,  the  feces  contained  about  0.5  kg.  of  dry  matter,  irrespective 
of  the  previous  feed-level. 

(6)  Smaller  amounts  of  urine  were  voided  during  submaintenance  than 
during  maintenance  or  pasture  feeding.  The  volume  decreased  as  the  fast 
progressed,  the  lower  level  of  excretion  being  noted  in  the  fasts  starting 
at  the  low  feed-level.  The  volume  was  seemingly  independent  of  the 
environmental  temperature  and  the  water  intake.  A  maximum  individual 
voiding  of  3,048  grams  was  shown  by  one  steer  on  the  fifth  day  of  one 
of  the  fasts  following  pasture  feeding-  Small  amounts  of  less  than  100 
grams  were  sometimes  passed.  Large  changes  in  the  content  of  the  bladder 
thus  seem  possible,  even  under  the  restricted  conditions  of  fasting. 

(7)  Extensive  chemical  analyses  of  the  steers'  urines  were  made.  The 
effect  of  fasting  was  to  change  the  composition  of  the  urine  from  one 
containing  a  relatively  low  per  cent  of  urea  and  significantly  high  amounts 
of  hippuric  acid  and  amino  acids  to  one  in  which  the  nitrogen  distribution 
on  the  percentage  basis  was  similar  to  that  in  the  urine  of  man  when 
eliminating  approximately  4  grams  of  nitrogen.  The  ammonia  content 


SUMMARY 


237 


was  extremely  low  and  was  not  increased  during  fasting.  The  content 
of  ketone  bodies  was  low.  This,  together  with  the  low  ammonia-content, 
indicates  a  lack  of  acidosis  during  fasting.  In  the  two  larger  animals  the 
creatinine  excretion  was  relatively  constant,  and,  per  kilogram  of  body- 
weight,  was  similar  to  that  of  man.  Little  or  no  creatine  was  excreted  by 
the  two  larger  animals  during  fasting,  but  the  two  younger  and  smaller 
animals  excreted  noticeable  amounts. 

(8)  The  total  loss  of  nitrogen  varied  with  the  length  of  the  fast  and 
the  character  of  the  preceding  ration,  being  notably  low  in  the  fasts  after 
submaintenance  feeding. 

(9)  The  steers  seemed  to  adjust  themselves  temperamentally  to  fasting 
even  more  rapidly  than  to  a  submaintenance  regime.  After  the  second  day 
no  particular  irritation  or  craving  for  feed  was  shown.  No  signs  of  lack 
of  vigor  were  exhibited,  the  steers  appearing  as  strong  and  healthy,  even 
on  the  last  day  of  the  14-day  fast,  as  in  the  early  stages  of  fasting. 

(10)  The  animals  became  more  quiet  and  inert  in  their  muscular  exer¬ 
tions  as  the  fast  progressed,  spending  a  larger  proportion  of  the  time  lying 
down  than  when  on  feed. 

(11)  Rumination  practically  ceased  after  the  second  day,  persisting 
longer  after  a  dry  ration  than  after  pasture  feeding- 

(12)  The  heart-rate  was  lower  during  the  periods  of  submaintenance 
feeding  and  seemingly  more  rapid  at  the  lower  environmental  temperatures. 
Fasting  resulted  in  an  almost  continuous  fall  in  the  heart-rate  to  a  level 
as  low  as  28  or  30  beats  per  minute  in  the  longest  fasts. 

(13)  The  respiration-rate  during  fasting  was  about  9  or  10  per  minute. 

(14)  The  normal  rectal  temperature  was  not  far  from  38.2°  C.  and  was 
singularly  unaffected  by  the  feed-level,  the  environmental  temperature, 
or  by  fasting. 

(15)  The  skin  temperature  was  measured  only  during  the  fasts  of  steers 
C  and  D  following  submaintenance  feeding.  The  small  amount  of  evidence 
secured  suggests  that  neither  fasting  nor  submaintenance  feeding  has  a 
marked  effect  upon  the  skin  temperature,  but  that  environmental  tempera¬ 
ture  plays  a  large  role. 

(16)  The  respiratory  quotient,  when  the  steer  was  receiving  feed  regu¬ 
larly,  was  about  1.00  or  above,  depending  somewhat  upon  the  character 
of  the  feed  and  the  time  elapsing  after  feed  had  been  eaten.  On  the  first 
day  of  fasting  the  quotient  was  about  0.82  or  0.83.  On  the  second  and 
third  days  it  was  still  lower,  but  after  the  third  day  remained  fairly  con¬ 
stant  at  about  0.70,  indicating  that  the  steer  was  burning  essentially  fat. 

(17)  The  heat-production  decreased  markedly  during  the  first  few  days 
of  fasting,  and  less  markedly  thereafter.  Uniformity  in  the  heat-production 
per  square  meter  of  body-surface  appeared  with  steer  C  on  about  the  fourth 
day  but  not  until  the  seventh  or  eighth  day  with  steer  D.  The  metabolic 
level  of  steer  D  was  distinctly  higher  than  that  of  steer  C  in  practically 
all  instances,  in  part  explained  by  his  greater  restlessness.  A  higher 
metabolism  was  noted  with  steers  E  and  F  when  fasting  after  submainte¬ 
nance  feeding,  indicating  the  higher  metabolism  of  the  younger  protoplasm. 

(18)  The  short  respiration  experiment  of  four  half-hour  periods,  even 
when  the  animal  is  standing  the  entire  time,  gives  a  computed  heat- 


238 


METABOLISM  OF  THE  FASTING  STEER 


production  not  far  from  that  found  in  24-hour  periods  when  the  animal 
is  allowed  to  lie  or  stand  at  will. 

(19)  In  the  4-day  respiration  experiments  a  somewhat  higher  heat- 
production  was  noted  with  alfalfa  hay  than  with  timothy  hay,  when  a 
maintenance  ration  was  fed.  The  submaintenance  level  of  metabolism 
was  much  lower  than  the  maintenance  level  and,  referred  to  body-weight 
or  body-surface,  was  essentially  the  same  with  both  steers,  regardless  of 
the  character  of  the  ration. 

(20)  The  environmental  temperature  had  practically  no  influence  upon 
the  metabolism  when  the  animal  was  receiving  a  maintenance  ration  of 
timothy  hay  or  when  fasting  after  such  a  ration.  At  the  submaintenance 
level  of  nutrition  with  timothy  hay,  however,  a  higher  metabolism  was 
noted  with  a  low  environmental  temperature,  whether  the  animal  was 
receiving  feed  or  was  fasting.  The  effect  was  apparently  not  proportional 
to  the  difference  in  temperature. 

(21)  A  difference  of  from  20  to  30  per  cent  between  the  metabolism  in 
the  lying  and  in  the  standing  position  was  noted  on  days  with  feed.  In 
some  instances  this  difference  diminished  during  fasting  and  practically 
disappeared  after  the  second  or  third  day,  but  in  other  instances  it  per¬ 
sisted  even  to  the  fourth  or  fifth  day.  The  correction  for  this  difference 
is  not  so  important  when  the  value  of  different  feeds  is  being  compared,  as 
it  is  when  an  approximation  of  the  true  fasting  katabolism  is  desired.  When 
cattle  have  been  fed  maintenance  rations,  a  sufficiently  close  approximation 
of  the  fasting  katabolism  can  be  determined  in  general  while  they  are 
standing,  about  32  hours  after  the  last  food,  and  if  a  satisfactory  reduction 
is  made  for  lying  in  the  measurement  thus  obtained,  the  basal  metabolism 
per  24  hours  lying  may  be  computed.  This  procedure  should  give  a  value 
which  is  suitable  as  a  base-line  in  studies  of  the  superimposed  effects  of 
various  factors,  provided  the  experiments  are  made  shortly  after  this  basal 
determination. 

(22)  The  level  in  the  plateau  of  metabolism  varied  with  the  different 
seasons  of  the  year  and  with  the  quantity  and  character  of  the  ration. 
Thus,  the  so-called  basal  metabolism,  when  once  attained  after  withholding 
feed,  was  seemingly  not  constant  with  the  same  animal,  even  if  he  had 
been  previously  upon  a  maintenance  ration,  for  a  higher  plateau  was  noted 
after  timothy  than  after  alfalfa  hay.  Submaintenance  feeding,  particularly 
with  alfalfa  hay,  lowered  the  level  of  the  fasting  metabolism  markedly. 
Since  it  is  impossible  with  steers  to  insure  complete  muscular  repose  at 
any  time  desired  and  complete  cessation  of  digestive  activity  (except  after 
4  or  5  days  without  food) ,  it  is  debatable  whether  any  attempt  to  secure 
the  equivalent  of  basal  conditions  in  man  is  feasible.  Furthermore,  it  does 
not  seem  necessary  in  general  practical  problems  to  determine  this 
equivalent. 

(23)  The  probable  basal  energy  requirement  of  cattle  is  about  1,300 
calories  per  square  meter  of  body-surface  per  24  hours,  when  the  animal  is 
lying  the  entire  time,  save  during  prolonged  fasting  or  fasting  following 
extreme  undernutrition.  In  two  instances  the  heat-production  on  this 
basis  of  computation  was  1,060  and  1,190  calories.  These  abnormally  low 
values  are  in  part  explained  by  the  influence  of  a  sudden  transition  from 


SUMMARY 


239 


a  cold  to  a  warm  environment.  In  general,  however,  fasting  per  se,  pro¬ 
vided  the  level  of  nutrition  has  not  been  too  greatly  lowered  by  previous 
undernutrition,  results  in  a  heat-production  per  square  meter  of  body- 
surface  per  24  hours  much  nearer  1,700  calories,  when  the  animal  is  standing. 

(24)  A  comparison  of  the  actually  measured  fasting  katabolism  with 
that  computed  from  the  metabolism  on  maintenance  and  submaintenance 
rations  shows  that  the  computation  method  gives  results  too  low.  Since 
the  submaintenance  ration  was  fed  for  three  weeks  or  more  before  its  effect 
was  measured,  the  metabolism  was  determined  not  only  under  conditions 
of  less  digestive  activity  due  to  the  reduction  in  feed  but  during  the  initial 
stage  of  undemutrition,  which  has  been  shown  to  lower  metabolism  greatly. 
It  is  suggested  that  the  more  logical  method  might  be  to  measure  the 
metabolism  during  a  5-day  respiration  experiment,  in  which  the  first  two 
days  would  represent  maintenance  feeding  and  the  last  three  days  sub¬ 
maintenance  feeding.  The  third  day  would  thus  be  a  transitional  period 
and  the  level  of  the  metabolism  on  the  fourth  and  fifth  days  would  be 
that  caused  by  the  reduced  ration  before  the  effect  of  undernutrition  was 
manifested. 

(25)  The  steers  were  extremely  slow  about  eating  after  a  fast,  taking 
hours  to  consume  even  1  or  2  kg.  of  hay  but  consuming  the  grain  with 
greater  relish.  The  metabolism  increased  almost  immediately  after  the 
animal  was  fed,  the  size  of  the  increase  depending  somewhat  upon  the 
time  occupied  in  eating  the  relatively  small  amounts  consumed.  After 
the  initial  response  the  metabolism  was  not  further  stimulated. 

(26)  The  ingestion  of  7  kg.  of  hay  produced,  not  during  the  height  of 
digestion  but  throughout  an  entire  24-hour  period,  an  increase  in  the  total 
heat-production  of  50  per  cent  in  the  case  of  timothy  hay  and  60  per  cent 
in  the  case  of  alfalfa  hay. 

(27)  The  standard  metabolism  was  frequently  lower  at  the  lower  envi¬ 
ronmental  temperatures.  Differences  in  the  activity  of  the  steers  obscured 
the  results  somewhat,  but  it  is  concluded  that  the  temperature  effect  is 
much  less  with  these  large  ruminants  than  with  other  animals. 

(28)  When  the  adult  animals  had  been  upon  full  feed  and  were  pre¬ 
sumably  in  a  maintenance  condition,  they  responded  definitely  to  a  sub¬ 
maintenance  ration  in  that  they  showed  a  persistently  low  metabolism. 
Animals  a  year  old,  however,  did  not  react  so  rapidly  to  reduction  in  feed, 
although  when  they  had  reached  the  age  of  21/2  years  a  submaintenance 
regime  of  only  3  weeks  also  resulted  in  a  distinctly  lower  metabolism. 

ADDENDUM 

Since  this  report  was  sent  to  the  printer,  several  publications  from  other 
institutions  have  appeared  which  are  of  interest  in  this  connection.  These 
appeared  too  late,  however,  to  be  discussed  in  this  monograph,  and  we  can 
here  only  call  attention  to  the  place  of  publication.0 

°  Forbes,  Braman,  Kriss,  Fries,  et  al.,  Journ.  Agric.  Research,  1926,  33,  p.  579. 

Forbes,  Fries,  Braman,  and  Kriss,  Journ.  Agric.  Research,  1926,  33,  p.  591. 

Fries,  Beretning  fra  N.  J.  F.’s  Kongress,  Oslo,  June,  1926. 

Titus,  Journ.  Agric.  Research,  1926,  33,  p.  887. 


ACKNOWLEDGMENTS 

The  experimental  work  in  connection  with  the  research  reported  in  this 
monograph  was  entirely  carried  out  at  Durham,  New  Hampshire,  under 
the  direction  of  the  junior  author.  Most  of  the  routine  work,  involving  the 
details  of  handling,  weighing,  feeding,  and  watering  of  the  animals,  of 
taking  daily  records  of  pulse,  body  temperature,  and  other  body  measure¬ 
ments,  was  in  the  hands  of  Mr.  A.  D.  Littlehale.  Assisted  by  chemically 
trained  students,  he  also  carried  out  the  preparation  of  rations  and  the 
sampling  and  weighing  of  feeds,  feces,  and  urine. 

The  gas  analyses  during  the  second  year’s  work  of  this  series  were  made 
by  Mrs.  Lois  A.  Ritzman.  With  this  exception,  all  the  gas  analyses  were 
made  by  Miss  Helen  M.  Hilton,  who  also  had  charge  of  the  routine  work 
connected  with  the  operation  of  the  respiration  chamber.  For  their  fidelity 
and  patience  we  are  deeply  indebted. 

The  analyses  of  feed  and  excreta  for  the  first  four  fasts  were  made  by 
Mr.  J.  A.  Gallagher,  under  the  direction  of  Dr.  H.  R.  Kraybill,  chemist 
of  the  New  Hampshire  Experiment  Station.  Later  all  these  determinations 
were  taken  over  by  Dr.  Thome  M.  Carpenter,  of  the  Nutrition  Laboratory 
staff,  who  was  assisted  in  the  details  of  the  determinations  by  Messrs.  P. 
P.  Saponaro,  E.  L.  Fox,  and  E.  S.  Mills,  and  Miss  D.  L.  Tibbetts.  The 
computations  of  the  results  of  these  chemical  analyses  were  carried  out 
by  Mr.  W.  H.  Leslie  with  his  characteristic  accuracy  and  thoroughness. 

The  editing  of  this  report,  as  indeed  the  one  preceding  it,  was  in  the 
capable  hands  of  Miss  Elsie  A.  Wilson. 


240 


SUBJECT  INDEX 


pxaa 


Acid  bodies,  Index  of  fasting  condition .  8 

In  urine . 121 

Stimulus  to  metabolism .  7,228 

Acidosis .  124 

Activity  (muscular),  degree  of,  during  respiration  experiments . 175,190,229 

During  fasting . 135,237 

Kymograph  records  of .  135 

Types  of .  6 

Age,  influence  on  creatine  excretion . 120,121 

creatinine  coefficient .  122 

creatinine  excretion .  120 

metabolism . 172,177,180,191,229,233,234,239 

nitrogen  in  urine .  122 

Animals  used .  38 

Individuality  in . 164,180,191 

Psychological  duplicates . 62-63 , 84 , 235 

Apparatus,  changes  in . 24-37 

Gas-analysis  (Carpenter) . 31-36 

Motor-generator .  25 

Respiration  chamber.  Additions  to .  26-28 

Aliquo ting  device .  29-31 

Disk  factor .  29-30 

Disk  opening,  size  of .  31 

Control  tests  with  carbon  dioxide .  36-37 

Swivel  stanchion .  27 

Appearance  of  animals  during  fasting . 136-137,237 

Appetite  after  fasting . 136 , 223 , 239 

Behavior,  during  fasting . 133-135,237 

realimentation .  136 

Body  conditions . 133-137 

measurements . 130-133 

position,  correction  of  basal  metabolism  measurements  for  differences  in . 211—213,238 

During  fasting . 135, 190 

During  metabolism  measurements . 40 , 152 

Effect  on  metabolism . . 151-152 , 202-203 , 238 

Method  of  recording  change  in .  134 

Body-surface,  computation  of.  . . . 153-156 

Law  of . 153,210-211,221-222 

Physiological  significance  of. . 221-222 

Relation  to  heat-production  v . !. . 221-222 


Body-temperature.  See  Temperature,  Rectal  and  Skin. 

Body-weight . 54-63 , 235 

Changes  in,  during  fasting .  56-63 

Index  of  change  in  body-tissue .  59,63 

Influence  of  water  intake  upon .  58 

Method  of  determining .  55 

Warm,  empty .  154 

Carbohydrates,  path  of  absorption  of . 19 

Carbon  dioxide,  calorific  value  of  . 146-148 

Carbon-dioxide  production,  during  feeding  and  fasting . 161-165,190 

Measurement  of,  as  index  of  heat-production . 145,161-165 

Ratio  between,  and  heat-production . 147-148 

Carnivora  and  herbivora  compared .  14 

Chest  circumference . 130-133 

Chronology  of  research .  41-53 

Condition  of  animal.  See  Body  conditions;  Flesh;  Nutrition,  state  of. 

Conditions,  experimental .  41-53 

Cost  of  digestion .  225 

Digestive  tract,  content  of.  See  Fill. 

Disposition,  during  fasting . 133-134 

Energy.  See  Heat-production;  Metabolism. 

Energy  transformations,  vital  activities  represented  by .  4-8 


'A 


241 


242 


METABOLISM  OF  THE  FASTING  STEER 


Environment.  See  Temperature,  environmental. 

Exchange,  gaseous.  See  Metabolism. 

Excreta.  See  Feces;  Urine. 

Fasts,  details  of  14-day  fasts . . 

Details  of  other  fasts . * . 

History  of  earlier  experimental  fasting . 

Length  of . 

Practical  value  of . 

Feces . . 

Amount  on  feed  and  fasting . 

Chemical  composition  of . 

Collection  of . ; . . . 

Device  for  separation  of,  from  urine  (with  cows) . . . 

Dry  matter  in . 

Frequency  of . . 

Influence  of  water  consumption  upon . 

Nitrogen  in . . . . 

Physical  characteristics  of . 

Feed,  amount  and  kind  given . 

Digestibility  of . .  . . •  > . 

Energy  involved  in  conversion  of . 

Influence  of,  on  body- weight  losses  during  fasting . 

feces . . 

metabolism  during  fasting . 

metabolism  after  fasting . 

metabolism  during  feeding . 

rectal  temperature . 

respiratory  quotient . 

standard  metabolism . 

Last,  before  fast . 

Productive  use  of . 

Provision  for,  in  respiration  chamber. . . 

Specific  dynamic  action  of . 

Feed-level  preceding  fasts . 

Fill,  after  fasting . 

Dry  matter  in . 

Influence  of  changes  in,  on  chest  girth . 

Minimum  amount  of . 

Moisture  content  of . 

Of  fasting  horse . . 

Per  cent  of  live  weight . 

Quantitative  changes  in,  during  fasting . 

Total . 

Variations  in,  during  undernutrition . 

Flesh.  See,  also,  Nutrition,  state  of. 

Condition  of,  during  fasting . 

Maximum  loss  of,  during  fasting . 

Food.  See,  Feed. 

Gas  analysis,  importance  of . 

Gas-analysis  apparatus  (Carpenter) . 

Gaseous  exchange.  See  Carbon-dioxide  production. 

Grain.  See  Feed. 

Hair . 

“Handling” . 

Hay.  See  Feed. 

Heart-rate . 

Heat-production.  See,  also,  Metabolism . 

During  fasting . . . 

Computation  of,  from  experiments  at  two  different  feed-levels 

In  3  consecutive  24-hour  periods . 

Per  500  kg.  of  body-weight . 

Per  square  meter  of  body-surface . 

Minimum . 

Humans  and  animals  compared . 

Plateau  in.  Incidence  of . . . 

Level  of . 

Total  per  24  hours . 


PAGE 

.  43-48 

.  48-52 

.  3-4 

.  55 

.  9-11 

. 81-97,236 

.  82-89 

.  91-97 

.  28,82 

.  106 

.  91-95 

.  86-89 

.  87 

.  95-97 

. 47,89-91 

.  42 

.  225 

.  6-8 

.  56-63 

.  82-89 

. 198-199 

. 39,222-223,239 

196-198,217,238,239 

.  143 

. 160-161 

. 231-234 

.  52-53 

.  5 

.  26-27 

.  7,225 

. 55,170 

.  154 

.  88 

.  130 

.  94-95 

. 17-18,92-94 

.  95 

.  81,97 

.  17 

. 16-17,88 

.  54 


136 

128 


31-32 

31-36 


.  137 

.  136 

. 137-141,237 

. 237-238 

. 171-192 

. 10,  209-218, 

223,  224,  234,239 

. 185-192 

.152,174-177,184 

.179-180,184-185 

. 216,218-222 

.  211 

.204^207,208,217 

. 206-209,238 

.171-174,180-184 


SUBJECT  INDEX 


243 


Heat  production — Continued  page 

During  2  days  on  feed  and  2  days  fasting . 192-203 

Influence  upon,  of  body  position . 151-152,202,211-213,238 

environmental  temperature . 219-221 

feed . 196-199 , 224-228 , 239 

Method  of  computing . , . 148-150 

Of  fasting  cows . 22 

Ratio  between,  and  carbon-dioxide  production . 23,147-148 

Relation  to  body-surface . 153,221-222 

Standard.  See,  also,  Metabolism . 228-234 

Herbivora  and  carnivora  compared . 14 

Humidity,  influence  of,  on  water  consumption .  80 

Index  of  metabolism,  heart-rate  as . 187 , 141 

State  of  nutrition  as . 131,133 

Individuality  in  animals . 135,180 

Insensible  perspiration . 19,40,63-75,235 

Investigations  of  others  on  fasting  ruminants . 12-13,104-106 

Katabolism.  See  Heat-production;  Metabolism. 

Ketosis .  124 

Literature  on  fasting  ruminants . 12-23,104-106 

Live  weight.  See  Body-weight. 

Lying.  See  Body  position. 

Maintenance.  See  Feed;  Feed-level;  Heat-production;  Metabolism. 

Metabolism.  See,  also,  Heat-production. 

Basal,  of  steers . 203-222,238 

Conditions  prerequisite  for  measurement  of . 150-152,203-204,218,221,238 

Correction  of,  to  standard  day  lying  and  standing . 211-213 

Basal,  of  humans,  effect  upon,  of  neutral  bath .  220 

Factors  lowering .  220 

Body  position  during  measurement  of . 40,152 

Fasting . 158—192 

Computation  of,  from  experiments  at  two  different  feed-levels . 10,209-218 

Error  in  method . 213—218,223,234,239 

Defined .  5 , 8—9 


Minimum  per  square  meter  of  body-surface . . . 

Plateau  in,  incidence  of . 

Level  of . 

Significance  of . 

Time  of  beginning  of . . . 

Four -day  experiments . 

Heart-rate  as  index  of . 

Influence  upon,  of  body  position . 

environmental  temperature 

feed . 

state  of  nutrition . . 

Measurements,  made  or  computed . . 

Method  of  presenting  data  on . 

Standard . 

Conditions  necessary  for  measurement  of .  . . . . 

Factors  affecting . 

Influence  upon,  of  environmental  temperature 

feed-level . 

Level  of,  at  start  of  fasts . . 

Methane . 


. 216,218-222 

. 204-207,217 

. 206-209,238 

.  4-5 

.  8,18 

. 192-203 

. 137,141 

. 151-152 

. 219-221 

. 222-228,239 

. 174 

. 144-150 

.  156 

. 228-234,239 

. 9,43,151,152,228 

. 228-234 

. 230-233 

. 231-234 

.  230 

22 , 144-145 , 149-150 , 160 , 204 


Methods: 

Chemical  analysis  of  mine .  107 

Collection  of  feces .  82 

urine .  07 

Computation  of  fasting  katabolism  of  steers . 209-218,223,239 

Conduct  of  4-day  respiration  experiments . 192-194 

24-hour  respiration  experiments .  188 

Determination  of  body-weight .  55 

body-surface . 153—156 

change  in  position  of  animal .  134 

Determination  of  chest-girth .  130 

heart-rate . 137 


244 


METABOLISM  OF  THE  FASTING  STEER 


Methods — Continued  paoh 

Determination  of  insensible  perspiration .  65 

rectal  temperature .  142 

respiration-rate . 141-142 

skin  temperature .  143 

water  consumption .  77 

Device  for  separation  of  urine  from  feces  (with  cows) .  106 

Presentation  of  gaseous  metabolism  data . 156—158 

Separation  of  feces  (Edin) .  88 

Nitrogen,  distinction  between  fecal  and  urinary . . .  129 

Economy . 122-123 

Fecal . 95—97 , 129 

Level . 124,126, 128 

Loss . 127-130 , 237 

Requirement  during  fasting  (Grouven) . 18 

Urinary . 115-116,128 

Nutrition,  state  of,  at  start  of  3-day  respiration  experiments .  189 

Indicated  by  chest  girth . 131,133 

Influence  of,  on  fasting  metabolism .  174 

heart-rate . 137,141 

metabolism  in  general .  222 

rectal  temperature .  143 

standard  metabolism . 231-234 

Oxygen,  calorific  value  of . 146, 150 

Periods  (in  chamber),  length  of . 156,185-187,192 

Perspiratio  insensibilis.  See  Insensible  perspiration. 


Plan  of  research . 39-40,237 

Plane  of  nutrition.  See  Feed-level;  Nutrition,  state  of. 

Problems  studied .  39-40 

Protein  (dry),  maximum  draft  upon,  during  fasting .  128 

Quotient,  respiratory . 36, 146, 158-161 , 167, 188-189,237 

Rations.  See  Feed. 

Realimentation,  influence  of,  on  metabolism . 222-223,239 

Residues,  intestinal.  See  Fill. 

Respiration  chamber.  See  Apparatus. 

Respiration-rate . 141-142 , 237 

Respiratory  exchange.  See  Carbon-dioxide  production;  Metabolism. 

quotient . 36,146, 158-161 , 167 , 188-189 , 237 

Rumination . 135 , 237 

Salivation .  135 

Salt . 81 

Size.  See  Body-weight. 

Skin .  137 

Soda-lime .  29 

Specific  dynamic  action  of  food .  7,225 

Standard  metabolism.  See  Metabolism. 

Standing.  See  Body  position. 

Submaintenance.  See  Feed;  Feed-level;  Heat-production;  Metabolism;  Under  nutrition. 

Surface  area.  See  Body-surface. 

Temperature, 

Environmental,  control  of .  25 

During  respiration  experiments .  170 

Influence  of,  on  heart-rate .  141 

metabolism . 175-177 , 182-184 , 200-202 , 206 , 219-221 , 230-231 , 233 , 238 

rectal  temperature .  143 

skin  temperature . 143-144 

urination . 99,103 

Rectal . • . 142,222,237 

Skin . 143-144,237 

U  ndernutrition .  4,39 

Behavior  during .  133 

Body-surface  estimations  during . 154 

Heart-rate  during .  137 

Influence  of,  on  standard  metabolism . 239 

nitrogen-level .  128 

Skin  temperature  during .  143 


SUBJECT  INDEX 


245 


Undernutrition — Continued 

Variations  in  fill  during . 

Urine . . . 

Acid  bodies  in . . . 

Amount  of,  during  fasting .  .  .  ■ . 

Analyses  by  other  investigators . 

Chemistry  of . 

Chlorides  in . . 

Collection  of . 

Conclusions  on  composition  of,  during  fasting . 

Creatine  in . 

Creatinine  coefficient . . . 

Preformed  creatinine  . . 

Total  creatinine . 

Device  for  separation  of,  from  feces  (with  cows) . . 

Frequency  of,  during  fasting . . 

Hourly  excretion  of,  during  fasting . 

Influence  on  amount  of,  of  environmental  temperature . 

feed-level . 

water  consumption . 

Litmus  test . 

Nitrogen  in . 

Economy . 

Hippuric  acid . 

Partition  of . 

Urea  and  ammonia . 

Of  fasting  horse . 

Phenols  in . 

Physical  properties  of . . . 

Phosphorus  in . 

Preservation  of . 

Relation  between  volume  and  dry  matter . 

nitrogen  content . 

water  consumption . 

Statistics  of  results  on . 

Timing  of  passing  of . 

Vigor  during  fasting . 

Vital  activities,  phases  of,  represented  by  energy  transformations 

Water . . . . 

Analysis  of . 

Consumption  of,  during  fasting . 

Influence  of,  on  body-weight  losses  during  fasting . 

urine  output . 

Influence  upon,  of  environmental  temperature . 

fasting  (intermittent) . 

feed-level . . . 

humidity . 

Method  of  determining . 

Provision  for,  in  respiration  chamber . . . 

Relation  between,  and  consistency  and  amount  of  feceB. 

dry  matter  in  feed . 

volume  of  urine . 

Refusal  of,  for  long  period . 

Temperature  of . 

Weight.  See  Body-weight. 


PAGE 

.  54 

. 97-126,236-237 

.  121 

. 99-103 

. 104-106 

. 104-126 

.  114 

. 25,27-28,97 

. 123-126 

. 120-121,126 

.  122 

.  120 

.  120 

.  106 

. 101-103 

.  101 

. 99,103 

.  99 

.  103 

. 98-99,123 

115-116, 121-122,127-128 

. 122-123 

. 119-120 

. . 116-121 

.  119 

.  14 

.  121 

.  103 

.  121 

.  107 

.  103 

. 115-116 

. 102-103 

. 107-114 

.  25 

.  134 

.  4-8 

. 75-81,236 

.  77 

.  79-81 

.  58 

. 81,103 

.  79 

.  79-80 

.  77-81 

. .  80 

.  77 

.  27 

.  87 

.  76,81 

.  103 

.  80-81 

.  77 


AUTHOR  INDEX 


PAGE 

Andersen,  A.  C . 145,149 

Armsby,  H.  P . 5,10, 

23,32,147,154,197,209,211 

Atwater,  W.  0 .  29 

Awrorow,  P .  75 

Baer,  J .  105 

Bailey,  C.  V .  35 

Bischoff,  Th.  L.  W .  15,63 

Blatherwick,  N.  R .  105 

Braman,  W.  W . 22,  23, 

32,  145,  147, 154,  204,211,214,215,239 

Brody,  S .  179 

Capstick,  J.  W . 21,22,201 

Carpenter,  T.  M. .  -  .6,34,104,105,107,225 

Cochrane,  D.  C .  214 

Cohn,  G . 12,95,139 

Csonka,  F.  A .  148 

Deighton,  T .  22 

Delcourt-Bernard .  220 

Dorno,  C .  184 

Du  Bois,  E.  F .  154 

Edin,  H .  88 

Elting,  E.  C .  179 

Ewing,  P.  V.,  and  F.  H.  Smith .  88 

Folin,  0 . 107,120,124 

Forbes,  E.  B . 59,106,116,152,202,239 

Fries,  J.  A  _ 23,  32,  40,  59, 106, 116, 147, 

151,154,197,202,211,214,239 

Grouven,  H . 3,15,59,63,97,104 

Haigh,  L.  D .  154 

Harris,  J.  A .  153 

Hasselbalch,  K.  A .  32 

Hawk,  P.  B .  3 

Hill,  A.  Y .  22 

Hogan,  A.  G .  154 

Howe,  P.  E .  3 

Ignatief .  20 

Jaquet,  A .  32 

Kellner,  O . 76 

Knoll,  A.  P .  139 


PAGE 

Kriss,  M.. 40, 59, 106, 116, 151, 202, 211, 239 

Krogh,  A .  151 

Lassaigne,  J.  L . 14 

Lefevre,  J . 220 

Ling,  S.  M . 148 

Lusk,  G .  8 

Magee,  H.  E .  202 

Magendie .  12 

Mayer,  Andre .  220 

Meeh,  K .  154 

Meissl,  E .  20 

Miles,  W.  R . 4,29,143,222 

Mpllgaard,  H . 149,212 

Moulton,  C.  R . 154,211 

Palladin,  A . 105 

Peters,  R.  A . 105 

Petren,  K . .115,124 

Pott,  A.  F . ...  141 

Prayon,  J .  105 

Rapport,  D .  148 

Root,  H.  F . .....40,64,68,75 

Roth,  P . 4,29,222 

Rubner,  M .  7 

Sanctorius .  63 

Sjollema,  B . 106 

Skouby,  C.  1 .  154 

Smith,  H.  Monmouth . 4,29,222 

Talbot,  F.  B .  148 

Tangl,  F .  21 

Tisdall,  F.  F .  107 

Titus,  H.  W .  239 

Trowbridge,  P.  F .  154 

Valenciennes,  A .  3 

Van  der  Zande,  J.  E. . . . 106 

Voit,  E . .15,63,210,211 

Weirzuchowski,  M .  148 

Weiss,  R .  148 

Willinger,  J . 107 

Wood,  T.  B . 21,201 

Zuntz,  N .  19,32 


246 


I 


